Biomass-resource-derived polyurethane, method for producing same, and biomass-resource-derived polyester polyol

ABSTRACT

The invention relates to a method for producing a biomass-resource-derived polyurethane, which comprises: reacting a dicarboxylic acid and an aliphatic diol to produce a polyester polyol; and reacting the polyester polyol and a polyisocyanate compound, wherein the dicarboxylic acid contains at least one component derived from biomass resources, a content of an organic acid in the dicarboxylic acid is more than 0 ppm and not more than 1,000 ppm relative to the dicarboxylic acid, and a pKa value of the organic acid at 25° C. is not more than 3.7.

TECHNICAL FIELD

The present invention relates to a biopolyurethane derived from novelpolyester polyol based biomass resources and a method for producing thesame and to a biomass-resource-derived polyester polyol. Specifically,the present invention relates to a polyurethane derived frompolyester-polyol-based biomass resources having an excellent balance inphysical properties such as mechanical physical properties, moldingoperability, etc., which are useful for applications over a wide rangeinclusive of synthetic or artificial leathers, foamed resins for shoesole, thermoplastic resins, thermosetting resins, paints, laminatingadhesives, elastic fibers, and the like, all of which are producedusing, as a raw material, a biomass-resource-derived polyester polyol.

BACKGROUND ART

A main soft segment part of polyurethane resins which have beenconventionally produced on an industrial scale, namely a polyol, isclassified into a polyether type represented by polypropylene glycol andpolytetramethylene glycol, a polyester polyol type represented bydicarboxylic acid based polyesters, a polylactone type represented bypolycaprolactone, and a polycarbonate type obtained by reacting acarbonate source and a diol (Non-Patent Document 1).

Of these, though the polyether type is excellent in hydrolysisresistance, flexibility, and elasticity, it is considered to be inferiorin mechanical strength such as abrasion resistance, flexibilityresistance, etc., heat resistance, and weather resistance. On the otherhand, though the conventional polyester type is improved in heatresistance and weather resistance, it cannot be used depending upon anapplication because hydrolysis resistance of an ester segment thereof islow. Though the polylactone type is considered to be a slightly betterin hydrolysis resistance as compared with adipates, it is unable tocompletely suppress the hydrolysis because it similarly has an estergroup.

Furthermore, though the polycarbonate type is excellent in hydrolysisresistance and durability, it involves such a drawback that handlingoperability is poor because a solution viscosity of a polyol itself or apolyurethane produced using this as a raw material is high. In addition,though it is also proposed to use these polyester type, polyether type,polylactone type, and polycarbonate type upon being mixed andcopolymerized, the respective drawbacks cannot be completely compensatedyet.

In addition, in recent years, global-scale awareness concerningenvironmental issues is increasing, and raw materials derived frombiomass resources such as plants, etc. but not petroleum-derived rawmaterials affecting the warming of the earth are expected. However,almost all of the foregoing polyols are derived from petroleum exclusiveof an extremely part of raw materials.

Furthermore, in polyester polyols which are most widely used at present,polyester polyols synthesized from adipic acid are leading. However, inproducing adipic acid, a nitric acid oxidation method is adopted, andthere is present an environmental issue that N₂O which is conspicuouslylarge in a warming effect following the production as compared with CO₂.

Then, in order to solving these problems, polyester polyols having avariety of structures are proposed. For example, there is a method forforming a polyester polyol by mixing and copolymerizing succinic acid asa dicarboxylic acid other than adipic acid and a diol without adoptingnitric acid oxidation for the production thereof, specially a method ofco-mixing succinic acid and an oligomer of ethylene glycol (PatentDocument 1).

But, though polyester polyols using petroleum-derived succinic acid andpolyurethanes produced therefrom are known and industrially produced,the polyester polyols using succinic acid as a raw material aregenerally poor in handling properties.

For example, the polyester polyols using succinic acid involved suchproblems that reaction control in the polyurethane reaction isdifficult; the molecular weight of a polyurethane resin is liable toincrease; in the case of using a polyisocyanate with low reactivity,etc. as a raw material, the polyurethane reaction becomes instable; andthe like. In addition, as compared with those produced using generallywidely used adipic acid as a raw material, the resulting polyurethaneresins have such properties that as a physical property of the resin,are high in hardness and high in elastic modulus of tensile strength,and their applications for use were restricted.

On the other hand, from the viewpoint of protecting the globalenvironment in the recent years, polyurethane resins derived frombiomass resources are demanded. However, sebacic acid and castor oil aremerely used in small amounts for limited applications, and polyurethaneraw materials derived from biomass resources have been expected.

In the recent years, there is disclosed a technology for producing apolyester polyol using, as a raw material, biosuccinic acid obtained bythe fermentation method (Patent Document 2). However, a polyurethaneusing the polyester polyol produced by the technology described inPatent Document 2 merely exhibits mechanical characteristics equal tothose in the case of using a polyester polyol produced using, as a rawmaterial, succinic acid derived from petroleum resources.

In the light of the above, according to any of the foregoing methods,the resulting polyester polyols are not ones having a balance ofphysical properties of the polyester polyol per se, good handlingproperties, color, and a balance of easiness of reaction control ormechanical physical properties when formed into a polyurethane. Thus,the development thereof has been expected.

RELATED ART DOCUMENT Non-Patent Document

-   Non-Patent Document 1: Fundamentals and Applications in    Polyurethanes, page 96-105, supervised by MATSUNAGA, Katsuji,    published by CMC Publishing Co., Ltd, issued in November 2006

Patent Document

-   Patent Document 1: JP-A-2009-96824-   Patent Document 2: International Publication No. 2008/104541

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

According to investigations made by the present inventors, in thetechnology described in Patent Document 1, succinic acid obtained frompetroleum resources is used. In general, in a process of producingsuccinic acid from petroleum resources, malic acid is formed as aby-product and incorporated as an impurity into the succinic acid. But,it was not mentioned that the incorporation of malic acid as anexcessive impurity adversely affects physical properties of apolyurethane, such as easiness of reaction control and flexibility.

For example, in succinic acid obtained from petroleum resources, malicacid is in general contained in an amount of from about 1,500 to 5,000ppm relative to succinic acid, and its content largely varies dependingupon a production lot. For that reason, as a result of extensive andintensive investigations, it has become clear that polyurethanesobtained from the subject succinic acid are not constant in physicalproperties; and that stable operations are hardly achieved in aproduction step thereof. Furthermore, the fact that that control of theamount of malic acid is important for stable production of apolyurethane using succinic acid as a raw material has been clarified.But, it is not industrially easy to remove this malic acid.

In addition, from a separate viewpoint, it may be considered that malicacid takes on the responsibility of regulating the strength of thepolyurethane and regulating a solution viscosity at the time ofproduction, and it is not always unnecessary as a component to be madecoexistent with succinic acid. As a result of extensive and intensiveinvestigations, it has become clear that in view of regulating desiredperformances of the polyurethane, malic acid is a component, the contentof which is to be controlled appropriately.

On the other hand, it is known that malic acid is formed as a by-productin producing biosuccinic acid (see International Publication No.2005/030973). As compared with succinic acid obtained from petroleumresources, the content of malic acid at the time of completion of afermentation reaction of biosuccinic acid is conspicuously large;however, the content of malic acid is in general reduced in a subsequentpurification step.

However, random purification against malic acid does not reach a levelof biosuccinic acid to be used as a raw material of a biopolyurethane ina practical level, and in its application, purification to the purposeor any means at the time of a production step or the like are necessary,and it was difficult to achieve practice implementation by merelyapplying the conventional biosuccinic acid to a biopolyurethane.

For example, Patent Document 2 discloses a biopolyurethane usingbiosuccinic acid. However, though it is disclosed that the succinic acidraw material to be used for the biopolyurethane is used upon beingpurified, details regarding its steps and the like are not described.

Then, Patent Document 2 describes that physical properties of theresulting polyester polyol and polyurethane are equal to those in thecase of using succinic acid obtained from petroleum resources. That is,according to the usual conventional purification methods, the amount ofmalic acid cannot be controlled, and it was still difficult to produce apolyurethane in a practically useful level.

In addition, in the biopolyurethane produced by the technology of PatentDocument 2, a problem of coloration remains, and it is the presentsituation that the technology has not reached the production of abiopolyurethane in a practically useful level yet.

Then, in view of the foregoing background art, the present invention hasbeen made, and problems thereof are to provide a polyurethane, in whicha molecular weight thereof is easily controllable and which is excellentin mechanical characteristics such as flexibility, etc. and less incoloration, and a biopolyester polyol for producing a biopolyurethane.

Means for Solving the Problems

In order to solve the foregoing problems, the present inventors madeextensive and intensive investigations. As a result, it has been foundthat by controlling a content of a specified organic acid in abiopolyurethane to a specified range, more specifically by strictlycontrolling an organic acid contained in a dicarboxylic acid and havinga pKa value at 25° C. of not more than 3.7 (this organic acid will behereinafter sometimes referred to simply as “organic acid”) during aperiod of from a production step to production of a polyurethane,thereby enabling one to largely affect a molecular weight in theproduction of a polyurethane and mechanical physical properties of theresulting polyurethane, such as flexibility, elasticity, etc., abiopolyurethane in a practically useful level, which is excellent inmechanical physical properties, production stability, and the like, anda polyester polyol that is also a raw material of the biopolyurethaneare obtained, leading to the present invention.

Specifically, the gist of the present invention is as follows.

1. A method for producing a biomass-resource-derived polyurethane, whichcomprises: reacting a dicarboxylic acid and an aliphatic diol to producea polyester polyol; and reacting the polyester polyol and apolyisocyanate compound, wherein the dicarboxylic acid contains at leastone component derived from biomass resources, a content of an organicacid in the dicarboxylic acid is more than 0 ppm and not more than 1,000ppm relative to the dicarboxylic acid, and a pKa value of the organicacid at 25° C. is not more than 3.7.2. The method for producing a biomass-resource-derived polyurethaneaccording to the item 1 above, wherein the at least one component of thedicarboxylic acid is one derived from biomass resources.3. The method for producing a biomass-resource-derived polyurethaneaccording to the item 1 or 2 above, wherein the dicarboxylic acidcontains succinic acid derived from biomass resources.4. The method for producing a biomass-resource-derived polyurethaneaccording to any one of the items 1 to 3 above, wherein the organic acidhaving a pKa value at 25° C. of not more than 3.7 has three or moreactive hydrogen groups per molecule.5. The method for producing a biomass-resource-derived polyurethaneaccording to any one of the items 1 to 4 above, wherein the organic acidhaving a pKa value of the organic acid at 25° C. of not more than 3.7 isat least one member selected from malic acid, tartaric acid, and citricacid.6. A biomass-resource-derived polyurethane, as obtained by theproduction method according to any one of the items 1 to 5 above.7. A biomass-resource-derived polyurethane, which at least comprises, asconstituent units, a dicarboxylic acid unit, an aliphatic diol unit, apolyisocyanate unit, and an organic acid unit having a pKa value at 25°C. of not more than 3.7, wherein the dicarboxylic acid contains at leastone component derived from biomass resources, and a content of theorganic acid unit is more than 0% by mole and not more than 0.09% bymole relative to the dicarboxylic acid unit.8. The biomass-resource-derived polyurethane according to the item 7above, wherein the at least one component of the dicarboxylic acid isone derived from biomass resources.9. The biomass-resource-derived polyurethane according to the item 7 or8 above, wherein the dicarboxylic acid contains succinic acid derivedfrom biomass resources.10. The biomass-resource-derived polyurethane according to any one ofthe items 7 to 9 above, wherein the aliphatic diol unit contains atleast one of an ethylene glycol unit and a 1,4-butanediol unit.11. The biomass-resource-derived polyurethane according to any one ofthe items 7 to 10 above, wherein the organic acid unit having a pKavalue at 25° C. of not more than 3.7 is an organic acid unit havingthree or more active hydrogen groups per molecule.12. The biomass-resource-derived polyurethane according to any one ofthe items 7 to 11 above, wherein the organic acid unit having a pKavalue at 25° C. of not more than 3.7 is at least one member selectedfrom malic acid, tartaric acid, and citric acid.13. The biomass-resource-derived polyurethane according to any one ofthe items 7 to 12 above, having a YI value (in conformity withJIS-K7105) of not more than 20.14. The biomass-resource-derived polyurethane according to any one ofthe items 6 to 13 above, having a molecular weight distribution (Mw/Mn)by the GPC measurement of from 1.5 to 3.5.15. A biomass-resource-derived polyester polyol for production of apolyurethane, which at least comprises, as constituent units, adicarboxylic acid unit, an aliphatic diol unit, and an organic acid unithaving a pKa value at 25° C. of not more than 3.7, wherein thedicarboxylic acid contains at least one component derived from biomassresources, and a content of the organic acid unit is more than 0% bymole and not more than 0.09% by mole relative to the dicarboxylic acidunit.16. The biomass-resource-derived polyester polyol according to the item15 above, wherein the at least one component of the dicarboxylic acid isone derived from biomass resources.17. The biomass-resource-derived polyester polyol according to the item15 or 16 above, wherein the dicarboxylic acid contains succinic acidderived from biomass resources.18. The biomass-resource-derived polyester polyol according to any oneof the items 15 to 17 above, having a number average molecular weight of500 or more and not more than 5,000.19. The biomass-resource-derived polyester polyol according to any oneof the items 15 to 18 above, wherein the organic acid unit is at leastone member selected from malic acid, tartaric acid, and citric acid.20. The biomass-resource-derived polyester polyol according to any oneof the items 15 to 19 above, having a value expressed as a Hazen colornumber (APHA value: in conformity with JIS-K0101) of not more than 50.21. An artificial leather or synthetic leather, as produced using thebiomass-resource-derived polyurethane according to any one of the items6 to 14 above.22. A polyurethane for shoe sole, as produced using thebiomass-resource-derived polyurethane according to any one of the items6 to 14 above.

Advantage of the Invention

In the production method of the present invention, in a step of reactinga dicarboxylic acid containing at least one component derived frombiomass resources and an aliphatic diol to produce a polyester polyol, acontent of an organic acid having a pKa value at 25° C. of not more than3.7, which is represented by malic acid in the dicarboxylic acid, iscontrolled to a specified amount or less. In consequence, a polyurethaneresin produced using the polyester polyol produced by the subject stepcan be used for a variety of applications because it has a linearstructure and has an excellent color. In addition, as a preferredembodiment, there is brought such an advantage that a polyurethanereaction is easily controllable by mediating a control step (forexample, a purification step, etc.) of an organic acid having a pKavalue at 25° C. of not more than 3.7.

In addition, the biomass-resource-derived polyurethane according to thepresent invention, which is produced using the polyester polyol producedby the foregoing step, has such a characteristic feature that it isexcellent in flexibility, while keeping mechanical strength and heatresistance that are characteristics of the conventional polyesterpolyol-derived polyurethane. In addition, the biomass-resource-derivedpolyurethane according to the present invention also has suchcharacteristic features that a viscosity of the resulting polyurethanesolution is low; and that operability of molding or coating is enhanced.

In consequence, for example, artificial or synthetic leathers,polyurethane resins for shoe sole, paints or coating agents, castpolyurethanes, and adhesives or sealants, which are produced using thebiomass-resource-derived polyurethane according to the presentinvention, are flexible and highly elastic and are improved in handlingproperties, as compared with polyurethanes produced using a polyesterpolyol using a petroleum-derived succinic acid as a raw material, andthey are extremely useful in industry.

Furthermore, in a preferred embodiment, the biomass-resource-derivedpolyurethane according to the present invention is derived from plants,is an environmentally friendly resin, and is enhanced inbiodegradability, and therefore, it is very useful.

MODES FOR CARRYING OUT THE INVENTION

Embodiments of the present invention are hereunder described in detail,but it should not be construed that the present invention is limited tothe following embodiments and can be carried out upon being modifiedwithin the scope of the gist thereof.

<Biomass-Resource-Derived Polyurethane>

A production method of a biomass-resource-derived polyurethane (in thepresent description, this polyurethane will be sometimes referred tosimply as “biopolyurethane” or “polyurethane”) is a method for producinga polyurethane including at least a step of reacting an aliphatic dioland a dicarboxylic acid to produce a polyester polyol; and a step ofreacting the polyester polyol and a polyisocyanate compound, wherein thedicarboxylic acid contains at least one component derived from biomassresources, and a content of an organic acid having a pKa value at 25° C.of not more than 3.7 in the dicarboxylic acid is more than 0 ppm and notmore than 1,000 ppm.

In addition, the biomass-resource-derived polyurethane according to thepresent invention is a biomass-resource-derived polyurethane containing,as constituent units, at least an aliphatic diol unit, a dicarboxylicacid unit, a polyisocyanate unit, and an organic acid unit having a pKavalue at 25° C. of not more than 3.7, wherein the dicarboxylic acid unitis one derived from biomass resources, and a content of the organic acidunit is more than 0% by mole and not more than 0.09% by mole relative tothe dicarboxylic acid unit.

Incidentally, the polyurethane as referred to in the present inventionmeans a polyurethane or a polyurethaneurea unless otherwise restricted,and it has hitherto been known that these two kinds of resins havesubstantially the same physical properties. On the other hand, so far asa structural characteristic feature is concerned, the polyurethane isone produced using a short-chain polyol as a chain extender, whereas thepolyurethaneurea is one produced using a polyamine compound as a chainextender.

(1) Dicarboxylic Acid:

Examples of the dicarboxylic acid component which is used in the presentinvention (in the present invention, this dicarboxylic acid componentwill be sometimes referred to simply as “dicarboxylic acid”) includealiphatic dicarboxylic acids or mixtures thereof, aromatic dicarboxylicacids or mixtures thereof, aromatic dicarboxylic acids or mixturesthereof, and mixtures of an aromatic dicarboxylic acid and an aliphaticdicarboxylic acid. Of these, those composed mainly of an aliphaticdicarboxylic acid are preferable.

It is meant by the terms “composed mainly of” as referred to in thepresent invention that in general, the content is preferably 50% by moleor more, more preferably 60% by mole or more, still more preferably 70%by mole or more, and especially preferably 90% by mole or more relativeto the total dicarboxylic acid unit.

Examples of the aromatic dicarboxylic acid include terephthalic acid,isophthalic acid, and the like. Examples of the derivative of anaromatic dicarboxylic acid include lower alkyl esters of an aromaticdicarboxylic acid. Specific examples of the lower alkyl ester of anaromatic dicarboxylic acid include methyl esters, ethyl esters, propylesters, butyl esters, and the like.

Of these, terephthalic acid and isophthalic acid are preferable as thearomatic dicarboxylic acid. In addition, dimethyl terephthalate anddimethyl isophthalate are preferable as the derivative of an aromaticdicarboxylic acid. For example, a desired aromatic polyester polyolpolyurethane can be produced by using an arbitrary aromatic dicarboxylicacid as in polyesters of dimethyl terephthalate or 1,4-butanediol.

Examples of the aliphatic dicarboxylic acid include aliphaticdicarboxylic acids or derivatives thereof. In general, the aliphaticdicarboxylic acid preferably has a carbon number of 2 or more and notmore than 40. In addition, the aliphatic dicarboxylic acid is preferablya normal chain or alicyclic dicarboxylic acid.

Specific examples of the normal chain or alicyclic dicarboxylic acidhaving a carbon number of 2 or more and not more than 40 include oxalicacid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanediacid, dimer acids, cyclohexanedicarboxylic acids, and the like. Ofthese, from the standpoint of physical properties of an obtainedpolymer, the aliphatic dicarboxylic acid is preferably adipic acid,succinic acid, sebacic acid, or a mixture thereof, and especiallypreferably one composed mainly of succinic acid.

In addition, examples of the derivative of an aliphatic dicarboxylicacid include lower alkyl esters of the foregoing aliphatic dicarboxylicacid, such as methyl esters, ethyl esters, propyl esters, butyl esters,etc., cyclic acid anhydrides of the foregoing aliphatic dicarboxylicacid, such as succinic acid, etc., and the like. Of these, a methylester of adipic acid or succinic acid, or a mixture thereof is morepreferable as the derivative of an aliphatic dicarboxylic acid.

These dicarboxylic acids can be used solely or in admixture of two ormore kinds thereof.

The dicarboxylic acid which is used in the present invention contains atleast one component derived from biomass resources. Examples of thepreferred component derived from biomass resources, which is containedin the dicarboxylic acid, include adipic acid, succinic acid, andsebacic acid. Of these, succinic acid is especially preferable.

In the present invention, as to the matter that the dicarboxylic acidcontains at least one component derived from biomass resources, in thecase where the dicarboxylic acid is a single kind, the component may bea mixture of, for example, succinic acid that is a petroleum-derived rawmaterial and, for example, succinic acid derived from biomass resources;and in the case where the dicarboxylic acid is a mixture of two or morekinds thereof, the component may be a mixture in which at least onemember of the dicarboxylic acids is one derived from biomass resources,or it may be a mixture of a dicarboxylic acid derived from biomassresources and a dicarboxylic acid as a petroleum-derived raw material.

In the case of a mixture of a dicarboxylic acid derived from biomassresources and a dicarboxylic acid as a petroleum-derived raw material,the dicarboxylic acid derived from biomass resources accounts forpreferably 20% by mole or more, more preferably 40% by mole or more,still more preferably 60% by mole or more, and especially preferably 90%by mole or more.

In addition, in the present invention, it is preferable that at leastone component of the dicarboxylic acid is one derived from biomassresources. This means that for example, when succinic acid is taken asan example as at least one component of the dicarboxylic acid, the wholeof the succinic acid is one derived from biomass resources.

Examples of the biomass resources as referred to in the presentinvention include those in which solar light energy is converted in aform of starch, sugar, cellulose, or the like due to photosynthesis ofplants and stored; animal bodies growing by eating vegetable bodies;products prepared by processing vegetable bodies or animal bodies; andthe like.

Of these, vegetable resources are more preferable as the biomassresources. Examples of the vegetable resources include wood, rice straw,chaff, rice bran, old rice, corn, sugar cane, cassava, sago palm, beancurd, corn cob, tapioca, bagasse, vegetable oil dregs, potato, soba,soybean, fats and oils, wastepaper, papermaking residue, aquaticresidue, livestock excrement, sewage sludge, food waste, and the like.

Of these, vegetable resources such as wood, rice straw, chaff, ricebran, old rice, corn, sugar cane, cassava, sago palm, bean curd, corncob, tapioca, bagasse, vegetable oil dregs, potato, soba, soybean, fatsand oils, wastepaper, papermaking residue, etc. are preferable; wood,rice straw, chaff, old rice, corn, sugar cane, cassava, sago palm,potato, fats and oils, wastepaper, and papermaking residue are morepreferable; and corn, sugar cane, cassava, and sago palm are the mostpreferable. In general, these biomass resources contain a nitrogenelement and a lot of alkali metals and alkaline earth metals such as Na,K, Mg, Ca, etc.

Then, though these biomass resources are not particularly limited, forexample, they are derived into a carbon source via a step of a knownpretreatment such as a chemical treatment with an acid or an alkali,etc., a biological treatment using a microorganism, a physicaltreatment, etc. and saccharification.

For example, though there is in general no particular limitation, theforegoing step includes a size reduction step by a pretreatment such aschipping, shaving or grinding of the biomass resources, etc.Furthermore, a pulverization step with a grinder or a mill is includedaccording to the need.

The thus microfabricated biomass resources are further derived into acarbon source via the pretreatment and saccharification step. Specificexamples of such a method include chemical methods such as an acidtreatment with a strong acid, for example, sulfuric acid, nitric acid,hydrochloric acid, phosphoric acid, etc., an alkali treatment, anammonia freezing steam explosion method, solvent extraction, asupercritical fluid treatment, an oxidizing agent treatment, etc.;physical methods such as pulverization, a steam explosion method, amicrowave treatment, electron beam irradiation, etc.; biologicaltreatments such as hydrolysis with a microorganism or enzymatictreatment.

Examples of the carbon source which is derived from the foregoingbiomass resources include fermentable carbohydrates such as hexoses, forexample, glucose, mannose, galactose, fructose, sorbose, tagatose, etc.;pentoses, for example, arabinose, xylose, ribose, xylulose, ribulose,etc.; disaccharides or polysaccharides, for example, pentosan,saccharose, starch, cellulose, etc.; fatty acids, for example, butyricacid, caproic acid, caprylic acid, capric acid, lauric acid, myristicacid, palmitic acid, parmitoleic acid, stearic acid, oleic acid,linoleic acid, linolenic acid, monocutinic acid, arachidic acid,eicosenoic acid, arachidonic acid, behenic acid, erucic acid,docosapentaenoic acid, docosahexaenoic acid, lignoceric acid, ceracoreicacid, etc.; polyalcohols, for example, glycerin, mannitol, xylitol,ribitol, etc.; and the like Of these, glucose, maltose, fructose,sucrose, lactose, trehalose, and cellulose are preferable.

A dicarboxylic acid is synthesized using such a carbon source by meansof a fermentation method utilizing microbial conversion with amicroorganism having production capability of a dicarboxylic acid, achemical conversion method including a reaction step such as hydrolysis,a dehydration reaction, a hydration reaction, an oxidation reaction,etc., or a combination of the fermentation method and the chemicalconversion method. Of these, the fermentation method by means ofmicrobial conversion is preferable.

The microorganism having production capability of a dicarboxylic acid isnot particularly limited so far as it is a microorganism havingproduction capability of a dicarboxylic acid. Examples thereof includeenterobacteria such as Escherichia coli, etc.; bacteria belonging to thegenus Bacillus; coryneform bacteria; and the like. Above all, the use ofan aerobic microorganism, a facultative anaerobic microorganism, or amicroaerophilic microorganism is preferable.

Examples of the aerobic microorganism include coryneform bacterium,bacteria belonging to the genus Bacillus, bacteria belong to the genusRhizobium, bacteria belonging to the genus Arthrobacter, bacteriabelonging to the genus Mycobacterium, bacteria belonging to the genusRhodococcus, bacteria belonging to the genus Nocardia, bacteriabelonging to the genus Streptomyces, and the like, with coryneformbacteria being more preferable.

The coryneform bacterium is not particularly limited so far as it isclassified into this group, and examples thereof include bacteriabelonging to the genus Cornebacterium, bacteria belonging to the genusBrevibacterium, bacteria belonging to the genus Arthrobacter, and thelike. Of these, bacteria belonging to the genus Cornebacterium or genusBrevibacterium are preferable, and bacteria classified intoCornebacterium glutamicum, Brevibacterium flavum, Brevibacteriumammoniagenes, or Brevibacterium lactofermentum are more preferable.

In the case of using a succinic acid-producing bacterium as themicroorganism having production capability of a dicarboxylic acid, asdescribed in the Examples as described later, it is preferable to use astrain having enhanced pyruvate carboxylase activity and reduced lactatedehydrogenase activity.

Though a reaction condition in the microbial transformation, such asreaction temperature and pressure, etc., depends upon the activity of amicroorganism to be chosen such as bacterial cells, fungi, etc., asuitable condition for obtaining a dicarboxylic acid may be chosendepending upon each case.

In the microbial transformation, when the pH becomes low, the metabolicactivity of the microorganism decreases, the microorganism stops theactivity, the production yield is deteriorated, or the microorganismbecomes extinct. Thus, a neutralizing agent is usually used.

In general, the pH within the reaction system is measured by a pHsensor, and the pH is regulated by the addition of a neutralizing agentsuch that the pH falls within a predetermined range. The pH value isregulated to the range where the activity is most effectively exhibiteddepending upon the kind of a microorganism to be used. An additionmethod of the neutralizing agent is not particularly limited, and it maybe continuous addition or intermittent addition.

Examples of the neutralizing agent include ammonia, ammonium carbonate,urea, hydroxides of an alkali metal, hydroxides of an alkaline earthmetal, carbonates of an alkali metal, and carbonates of an alkalineearth metal. Of these, ammonia, ammonium carbonate, and urea arepreferable.

Examples of the hydroxide of an alkali (alkaline earth) metal includeNaOH, KOH, Ca(OH)₂, Mg(OH)₂, etc., and mixtures thereof, and the like.In addition, examples of the carbonate of an alkali (alkaline earth)metal include Na₂CO₃, K₂CO₃, CaCO₃, MgCO₃, NaKCO₃, etc., and mixturesthereof, and the like.

The pH value is regulated to the range where the activity is mosteffectively exhibited depending upon the kind of a microorganism to beused. In general, the pH is preferably in the range of from 4 to 10, andmore preferably in the range of from about 6 to 9.

A fermentation liquid after the microbial transformation may be properlyconcentrated while taking into consideration operability or efficiencyin the subsequent purification step. Though a concentration method isnot particularly limited, examples thereof include a method ofcirculating an inert gas, a method of distilling off water by heating, amethod of distilling off water under reduced pressure, a combinationthereof, and the like. In addition, a concentration operation may beeither a batch operation or a continuous operation.

Incidentally, in the case of using a fermentation liquid, it ispreferable to use the fermentation liquid after removing themicroorganism. Though the removal method of a microorganism is notparticularly limited, examples thereof include settling separation,centrifugation, filtration separation, a combined method thereof, andthe like. The removal of a microorganism is industrially carried out bya method such as centrifugation, membrane filtration separation, etc.

Examples of the centrifugation include centrifugal settling, centrifugalfiltration, and the like. In the centrifugation, though its operationcondition is not particularly limited, in general, it is preferable toconduct the separation by a centrifugal force of from 100 G to 100,000G. In addition, both a continuous mode and a batch mode can be adoptedfor the operation.

In addition, examples of the membrane filtration separation includeprecise filtration, ultrafiltration, and the like, and these may becombined. Though a material quality of the membrane is not particularlylimited, examples thereof include organic membranes such as polyolefins,polysulfines, polyacrylonitrile, polyvinylidene fluoride, etc.; andmembranes of an inorganic material such as ceramics, etc. In addition,as an operation method thereof, any of a dead-end type and a cross-flowtype can be adopted. In the membrane filtration separation, themicroorganism often causes clogging of the membrane, and therefore, amethod in which after roughly removing the microorganism by means ofcentrifugation or the like, membrane filtration is carried out, or othermethod is adopted, too.

Embodiments of the production method of a dicarboxylic acid arehereunder described in detail. However, these descriptions arerepresentative examples of the embodiments, and it should not beconstrued that the present invention is limited thereto.

As the representative example of the production method of a dicarboxylicacid, a method for producing a dicarboxylic acid, which includes thefollowing steps I to V, is enumerated.

I. An extraction step of mixing of an aqueous solution containing adicarboxylic acid and a solvent for achieving phase separation from theaqueous solution and recovering the dicarboxylic acid in the solvent;

II. An extract phase concentration step that is a step of concentratingthe dicarboxylic acid recovered in the extraction step, in which a waterconcentration in the extract phase increases due to the concentration;

III. A crystallization step of depositing the dicarboxylic acid from aliquid after the extract phase concentration step;

IV. A solid-liquid separation step of recovering the dicarboxylic aciddeposited in the crystallization step; and

V. A crystallization mother liquid recycling step of returning at leasta part of a crystallization mother liquid after recovering thedicarboxylic acid obtained in the solid-liquid separation step into anyone of the steps before the crystallization step.

An embodiment of each of the steps is hereunder described in detail, butthe expressions of a dicarboxylic acid and succinic acid areparticularly limited and are applicable to the both.

[I. Extraction Step]

The extraction step is a step in which in producing a dicarboxylic acidfrom an aqueous solution containing a dicarboxylic acid obtained frombiomass resources, the aqueous solution containing a dicarboxylic acidand a solvent for achieving phase separation from the aqueous solutionare mixed, and the dicarboxylic acid is recovered in the solvent. Ingeneral, the extraction step preferably includes a contact step ofmixing an aqueous solution containing a dicarboxylic acid and a solventfor achieving phase separation from the aqueous solution to bring theminto contact with each other and a phase separation step of after thecontact step, subjecting the liquid to phase separation.

In the phase separation step, the aqueous solution and the solvent aresubjected to phase separation from each other. According tocircumstances, there is a concern that a phase containing a solidcontent (hereinafter sometimes referred to as “intermediate phase”) isformed at a phase interface, thereby allowing the intermediate phase tomake it difficult to separate the solvent phase (hereinafter sometimesreferred to as “extract phase”) and the aqueous solution phase(hereinafter sometimes referred to as “raffinate phase”) from eachother, or increasing an amount of impurities incorporated into theextract phase. Here, it is preferable to remove the intermediate phase.

In the case of carrying out the contact step by means of a batchoperation, the aqueous solution containing a dicarboxylic acid is addedwith the solvent capable of achieving phase separation from the aqueoussolution; the contents are thoroughly mixed; and thereafter, in thephase separation step, the extract phase, the intermediate phase, andthe raffinate phase can be separated and recovered by a method ofdischarging the extract phase, the intermediate phase, and the raffinatephase from the neighborhoods of the respective phases through outlets, amethod of successively discharging the phases from the bottom of acontainer used for the contact, or other method. The intermediate phasecontaining a large amount of a solid content can also be dischargedtogether with the extract phase, or can also be discharged together withthe raffinate phase.

In addition, for example, in the case of carrying out the contact stepby means of a continuous operation, in the phase separation step using acontact apparatus composed of a mixer section having a mixer for contactmixing the aqueous solution containing a dicarboxylic acid and thesolvent capable of achieving phase separation from the aqueous solutionand a settler section having a settler to be applied to a step ofallowing the mixed solution obtained by contact mixing to stand toachieve phase separation (sometimes referred to as “phase separationstep”) (the contact apparatus is sometimes referred to as “mixer-settlertype extractor”), the extract phase, the intermediate phase, and theraffinate phase can be recovered, respectively.

(Solid Content)

In the case of adopting the fermentation method with a microorganism atthe time of obtaining a dicarboxylic acid from a raw material derivedfrom biomass resources, in general, polymers having a high-orderstructure such as proteins, etc. are present as impurities in thefermentation liquid. The proteins, etc. are in general highly soluble inwater, and almost all of them are distributed into an aqueous solutionphase. However, a material in which the high-order structure thereofbreaks and which causes denaturation and is insoluble in both water anda solvent is partly present.

A solid content formed in the extraction process tends to gather in theneighborhood of a liquid-liquid interface. In general, in the batchextraction, even when the solid content is formed in the neighborhood ofa liquid-liquid interface, there is no significant problem in theoperation so far as the solid content is removed, and the extract phaseand the raffinate phase are recovered.

On the other hand, in the continuous extraction, in particular, in acountercurrent multi-stage extraction column, since the solid content iscontinuously formed, a hindrance is caused in liquid-liquid dispersionor liquid-liquid separation, and there is a concern that not only thestable operation is disturbed, but even the extraction cannot beachieved. In addition, when the liquid containing a solid content flowsinto the succeeding step, there is a concern that the succeeding step isadversely affected.

For example, since the extract phase containing a dicarboxylic acid asrecovered in the extraction step has a low dicarboxylic acidconcentration, there may be the case where the extract phase isconcentrated. However, when the solid content is present, the solidcontent attaches onto a heating surface of a reboiler, etc. and getsburnt thereon, thereby deteriorating heat transfer efficiency.Furthermore, the may be the case where a problem occurs on the materialquality depending upon the succeeding step.

In addition, in the case of using a dicarboxylic acid as a raw materialof the polyester polyol, it becomes clear that a nitrogenatom-containing component greatly participates in the polymer colortone.

Since the solid content contains a large amount of a protein denaturantand also contains a large amount of a nitrogen atom-containingcomponent, when the solid content is incorporate into a final product,there is a possibility that the color tone of the polymer is affected.In consequence, it is preferable to remove the solid content formed inthe extraction process by the extraction step.

(Removal of Solid Content)

Though a removal method of the solid content is not particularlyrestricted, it is preferable to selectively remove only the solidcontent.

For example, in the batch extraction, the solvent is added to theaqueous solution containing a dicarboxylic acid; the contents arethoroughly mixed; and thereafter, the extract phase, the intermediatephase containing a large amount of the solid content, and the raffinatephase can be separated and recovered, respectively.

In addition, in the continuous extraction, in a mixer-settler typeextractor composed of a mixer section having a mixer for mixing thefermentation liquid and the solvent and a settler section for subjectingthe mixed liquid to liquid-liquid separation, the extract phase, theintermediate phase containing a large amount of the solid content, andthe raffinate phase can be recovered, respectively by the settler.

As the mixer, any system may be adopted so far as the fermentationliquid and the solvent are thoroughly mixed, and examples thereofinclude a mixing tank, a static mixer, and the like. However, in thecase of using a mixing tank, air bubbles dragged into the mixing tank bystirring attach to the produced solid content and conspicuously hindersettling of the solid content in the succeeding settler, and therefore,a care is required to be taken for setting a stirring condition. Fromthe viewpoints of an extent of an operation tolerance range andequipment costs, the mixer is preferably a static mixer.

On the other hand, the type of the settler is not particularly limited.Examples thereof include a type of recovering the extract phase, theintermediate phase, and the raffinate phase, respectively by asingle-tank system; and a type of recovering the extract phase, theintermediate phase, and the raffinate phase, respectively by amulti-tank system.

Since the intermediate phase containing a large amount of the solidcontains the extract phase and the raffinate phase, the intermediatephase is subjected to solid-liquid separation to separate the solidcontent and the extract phase and/or the raffinate phase from eachother, whereby the extract phase and/or the raffinate phase can berecovered. Though the solid-liquid separation method is not particularlylimited, examples thereof include methods such as settling separation,filtration separation, etc.

In the settling separation, the solid content may be subjected tosettling separation in a gravitational field, or the solid content maybe subjected to settling separation in a centrifugal force field.However, from the standpoint of a settling rate, centrifugal settlingseparation is preferable. In addition, a system thereof may be either abatch operation or a continuous operation. Examples of a continuouscentrifugal settler include a screw decanter and a separation plate typecentrifugal settler.

In the filtration separation, its method is classified by a filtermaterial, a filtration pressure, a continuous operation or a batchoperation, and the like. However, it is not particularly limited so faras it is able to separate the solid content from the extract phaseand/or the raffinate phase. However, an opening of the filter materialis preferably 0.1 μm or more and not more than 10 μm. When the openingof the filter material is 0.1 μm or more, a penetrating flux is notexcessively small, and it is possible to prevent the matter that ittakes an excessive time for the filtration. On the other hand, when theopening of the filter material is not more than 10 μm, the separation ofthe solid content is sufficient.

In view of the fact that the material quality of the filter material isrequired to be insoluble in the solvent, it is preferable to use Teflon(registered trademark). In addition, any of a vacuum type, a pressuretype, or a centrifugation type can be adopted for the filtration.Furthermore, a system thereof may be either a continuous system or abatch system.

(Contact Apparatus)

As the contact apparatus, any apparatus may be used so far as it is ableto allow the aqueous solution containing a dicarboxylic acid and thesolvent to come into contact with each other and recover a solvent phaseand an aqueous solution phase. However, an apparatus capable of furtherremove the solid content is preferable. Above all, the above-describedmixer-settler type extractor which is simple and easy in operation ispreferable.

As the mixer, any system may be useful so far as it is able tothoroughly mix the aqueous solution containing a dicarboxylic acid andthe solvent capable of achieving phase separation from the aqueoussolution, and examples thereof include a container having a stirrer, astatic mixer, and the like. However, in the case of using a containerhaving a stirrer, air bubbles or the like dragged into the container bystirring attach to the produced solid content and conspicuously hinderphase separation of the solid content in the succeeding settler, andtherefore, it is preferable to achieve stirring under a condition underwhich air or the like is not dragged. From the viewpoints of an extentof an operation tolerance range and equipment costs, the mixer ispreferably a static mixer.

(Phase Separation Apparatus)

The settler may be any system so far as it is able to achieve phaseseparation of a liquid obtained after bringing the aqueous solutioncontaining a dicarboxylic acid and the solvent capable of achieving thephase separation from the aqueous solution into contact with each other.Examples thereof include a type of recovering the extract phase, theintermediate phase, and the raffinate phase, respectively by asingle-tank system; a type of recovering the extract phase, theintermediate phase, and the raffinate phase, respectively by amulti-tank system; a type of recovering each of the phases by means ofcentrifugation by a rotation apparatus; and the like.

Since in general, the intermediate phase containing a large amount ofthe solid content contains at least one liquid selected from a liquid ofthe extract phase and a liquid of the raffinate phase, the at least oneliquid selected from a liquid of the extract phase and a liquid of theraffinate phase can be separated and recovered by subjecting theintermediate phase to phase separation. The recovered liquid can bereturned to the step after the phase separation step and can also bereused in the step before the contact step. By reusing the recoveredliquid, the production efficiency of the dicarboxylic acid can beenhanced, and therefore, such is preferable.

The solid-liquid separation method is not particularly limited, andexamples thereof include settling separation, filtration separation, andthe like. In the settling separation, the solid content may be subjectedto settling separation in a gravitational field, or the solid contentmay be subjected to settling separation in a centrifugal force field.Centrifugal settling separation is preferable because the settling rateis increased.

A system of the operation of solid-liquid separation may be either abatch operation or a continuous operation. Examples of a continuouscentrifugal settler include a screw decanter and a separation plate typecentrifugal settler.

In the filtration separation, its method is classified by a filtermaterial, a filtration pressure, a continuous operation or a batchoperation, and the like. However, it is not particularly limited so faras it is able to separate the solid content from the extract phaseand/or the raffinate phase. However, an opening of the filter materialis preferably 0.1 μm or more and not more than 10 μm. When the openingof the filter material is 0.1 μm or more, a penetrating flux is notexcessively small, and it is possible to prevent the matter that ittakes an excessive time for the filtration. On the other hand, when theopening of the filter material is not more than 10 μm, the separation ofthe solid content is sufficient. In addition, since the material qualityof the filter material is required to be insoluble in the solvent, it ispreferable to use a filter material made of a fluorine based resin suchas Teflon, etc.

Any of a vacuum type, a pressure type, or a centrifugation type can beadopted for the filtration. Furthermore, a system thereof may be eithera continuous system or a batch system.

(Solvent)

Though the solvent which is used in the contact step is not particularlylimited so far as it is able to achieve phase separation from theaqueous solution containing a dicarboxylic acid, aninorganicity/organicity ratio (hereinafter sometimes abbreviated as “I/Ovalue”) is preferably 0.2 or more and not more than 2.3, and morepreferably 0.3 or more and not more than 2.0. By using such a solvent,it becomes possible to selectively extract the dicarboxylic acid andefficiently separate from impurities.

In addition, a solvent having a boiling point of 40° C. or higher atordinary pressure (one atmosphere), and more preferably, a solventhaving a boiling point of 60° C. or higher at ordinary pressure is used.In addition, a solvent having a boiling point of preferably not higherthan 120° C., more preferably not higher than 100° C., and especiallypreferably not higher than 90° C. at ordinary pressure is useful.

By using the foregoing solvent, it becomes possible to avoid danger ofignition of the solvent upon evaporation, a problem of a decrease ofextraction efficiency of the dicarboxylic acid to be caused due toevaporation of the solvent, and a problem that the solvent is hardlyrecycled. In addition, there is brought such an advantage that theamount of heat to be required at the time of separating the solventafter the use by means of distillation or the like, or reusing thesolvent upon purification may be minimized.

The inorganicity and the organicity are proposed by Organic ConceptionDiagram, “Systematic Organic Qualitative Analysis”, FUJITA, Yuzuru,Kazamashobo Co., Ltd. (1974). The inorganicity/organicity ratio isobtained by calculating an organicity and an inorganicity on the basisof numerical values set in advance for functional groups constituting anorganic compound and determining a ratio therebetween.

Examples of the solvent having an I/O value of 0.2 or more and not morethan 2.3 and having a boiling point of 40° C. or higher at ordinarypressure include ketone based solvents such as methyl ethyl ketone,methyl isobutyl ketone, acetone, etc.; ether based solvents such astetrahydrofuran, dioxane, etc.; ester based solvents such as ethylacetate, etc.; nitrile based solvents such as acetonitrile, etc.; andalcohols having a carbon number of 3 or more, such as propanol, butanol,octanol, etc.

I/O values and boiling points of respective solvents are shown in thefollowing table.

TABLE 1 I/O value of respective solvents I O I/O Boiling pointTetrahydrofuran 30 80 0.375 66.0 Methyl ethyl ketone 65 60 1.083 79.6Methyl isobutyl ketone 65 120 0.542 94.2 Acetone 65 40 1.625 56.1Acetonitrile 70 40 1.750 81.1 Ethyl acetate 85 80 1.063 77.2 Propanol100 60 1.667 97.2 Isobutanol 100 70 1.429 108.0 Octanol 100 160 0.625179.8 Dioxane 40 80 0.500 101.3

By the contact step, the dicarboxylic acid can be selectively extractedinto the solvent, and sugars, amino acids, and inorganic salts, all ofwhich are highly soluble in water, are distributed into the aqueoussolution phase. As a matter of course, a by-product salt formed in aprotonation step of the dicarboxylic acid salt is distributed into theaqueous solution phase and can be easily separated from the dicarboxylicacid.

For example, in the case where the by-product salt is ammonium sulfate,almost all thereof is recovered into the aqueous solution phase. At thesame time, ammonium sulfate is subjected to treatments includingconcentration, crystallization, drying, and the like together with theamino acids and sugars recovered into the aqueous solution phase, andthe amino acids and sugars can be recovered as ammonium sulfatecontaining organic contents. In view of the fact that the ammoniumsulfate appropriately contains organic materials, it is useful as afertilizer.

(Contact Operation)

In the contact operation, the operation for bringing the aqueoussolution containing a dicarboxylic acid and the solvent capable ofachieving phase separation from the aqueous solution into contact witheach other may be carried out by a single-stage or multi-stage manner,and it is preferably carried out by a multi-stage manner.

In addition, the solvent may be allowed to flow either concurrently orcountercurrently to the aqueous solution containing a dicarboxylic acid.The contact step may be carried out either continuously or batchwise. Anespecially preferred embodiment is an embodiment in which after mixingthe aqueous solution containing a dicarboxylic acid and the solvent by amixer settler, the mixture is subjected to liquid-liquid separation; anextract phase, an intermediate phase, and a raffinate phase areseparated and recovered, respectively; the intermediate phase issubjected to solid-liquid separation; and the separated and recoveredliquid is subjected to phase separation according to the need and thenreturned into a step after the phase separation step.

By the foregoing contact step of brining the solvent and the aqueoussolution containing a dicarboxylic acid into contact with each other,the dicarboxylic acid is extracted into the solvent. Here, the solventis added in an amount of preferably from 0.5 to 5 volume times, and morepreferably from 1 to 3 volume times the volume of the aqueous solutioncontaining a dicarboxylic acid at the temperature at the time ofcontact.

Though the temperature at the time of contact is not particularlylimited so far as it is a temperature at which the dicarboxylic acid isextracted, it is preferably from 30 to 60° C. When the contacttemperature is 30° C. or higher, problems such as an increase of theviscosity of the solvent, etc. are prevented; in view of the fact that atime required for settling of the formed solid content becomes long,floating of the solid content in the solvent phase is prevented; andincorporation of the solid content into the solvent phase is suppressed.On the other hand, when the contact temperature is not higher than 60°C., a decrease of the extraction rate of the dicarboxylic acid isprevented, and the efficiency is good.

A time at the time of contact is not particularly limited so far as itis a time at which the dicarboxylic acid is sufficiently extracted, andthough the contact time varies depending upon the contact apparatus orcontact condition, in general, it is preferably from one second to 5hours. When the contact time is one second or longer, the extraction ofthe dicarboxylic acid into the solvent phase is sufficient. On the otherhand, when the contact time is not longer than 5 hours, not only thematter that the apparatus becomes unnecessarily large is prevented, anaspect of which is efficient, but the progress of denaturation ofproteins coexistent in the dicarboxylic acid with the solvent isprevented, thereby suppressing an increase of the solid content.

A pressure at the time of contact is not particularly limited so far asit is a pressure at which the dicarboxylic acid is sufficientlyextracted. In the case where the contact is continuously carried out, itis in general operated at atmospheric pressure.

(Phase Separation Operation)

The phase separation operation in the phase separation step can becarried out by allowing the contents to stand in the tank for a certainperiod, or can be carried out by a centrifuge. The foregoingmixer-settler type extractor has a settler section for achieving phaseseparation by allowing the mixed liquid obtained by contact mixing tostand, and the phase separation can be achieved by allowing the liquidto stand in the settler section for a certain period. The phaseseparation step may be carried out either continuously or batchwise.

Though a temperature at the time of phase separation is not particularlylimited so far as it is a temperature at which of each of the phases canbe separated, it is preferably from 30 to 60° C., and it is preferableto conduct the treatment at a temperature of the same degree as that inthe contact operation. When the phase separation temperature is 30° C.or higher, an increase of the liquid viscosity is prevented to make iteasy to achieve the separation of the solid content; incorporation ofthe solid content into the solvent phase is prevented; and the amount ofthe solvent incorporating into the solid content can be suppressed. Onthe other hand, when the phase separation temperature is not higher than60° C., back extraction of the dicarboxylic acid into the aqueoussolution in the phase separation process can be prevented.

A time at the time of phase separation is not particularly limited sofar as it is a time at which the phase separation of each of the phasesis achieved, and though the phase separation time varies depending uponthe contact apparatus, the contact condition, and the phase separationmethod, in general, it is preferably from one minute to 5 hours. Whenthe phase separation time is one minute or longer, the phase separationbecomes sufficient; incorporation of the aqueous solution or the solidcontent into the solvent phase is prevented; and inversely,incorporation of the solvent or the solid content into the aqueoussolution phase can be suppressed. On the other hand, when the separationtime is not longer than 5 hours, the matter that the apparatus becomesunnecessarily large is prevented, an aspect of which is efficient.

In addition, a pressure at the time of phase separation is notparticularly limited so far as it is a pressure at which thedicarboxylic acid is sufficiently extracted. In the case where the phaseseparation is continuously carried out, it is in general operated atatmospheric pressure.

(Protonation Step)

At the time of recovering the dicarboxylic acid in the solvent in theextraction step, in the aqueous solution containing a dicarboxylic acid,in the case where the dicarboxylic acid is present as an aqueoussolution of a salt, there may be the case where an amount of thedicarboxylic acid and/or the dicarboxylic acid salt to be extracted intothe solvent capable of achieving phase separation from the aqueoussolution containing a dicarboxylic acid is small, and therefore, it ispreferable to add an acid to the aqueous solution to achieveprotonation.

For example, at the time of obtaining a dicarboxylic acid from a rawmaterial derived from biomass resources, in the case of obtaining itutilizing fermentation with a microorganism, there may be the case wherea hydrogen ion concentration (pH) of the fermentation liquid isregulated for the purpose of allowing the fermentation to efficientlyproceed. In the case of carrying out alkali neutralization, thedicarboxylic acid exists as an aqueous solution of a salt, andtherefore, it is especially preferable to conduct protonation. Forexample, in the case of using ammonia as a neutralizing agent in thefermentation operation, since the dicarboxylic acid exists as anammonium salt, it is preferable to conduct protonation with an acid.

A protonation step of adding an acid to the aqueous solution containinga dicarboxylic acid may be a step to be carried out at any stage so faras it is a step before the extraction step. Since the acid which is usedin the protonation step is required to achieve salt exchange with thedicarboxylic acid salt, in general, it is preferable to use an acidstronger than the dicarboxylic acid, namely an acid having an aciddissociation constant pKa smaller than the dicarboxylic acid, usually anacid having a pKa of less than 4.

The acid to be used may be either an organic acid or an inorganic acid,and it may be either a monovalent acid or a polyvalent acid. However, aninorganic acid is preferable. In the case of using sulfuric acid in theprotonation step, ammonium sulfate is formed as a by-product salt. Inthe present production method, the case where the inorganic salt is aby-product salt is preferable because an improvement in liquid-liquidseparation properties can be expected due to a salting out effect by theby-product salt in the extraction step.

Though an amount of the acid to be added varies depending upon theintensity of the acid, in general, the acid is added in an amount offrom about 0.1 to 5 equivalent times the amount relative to the cationconstituting the dicarboxylic acid salt. In general, the addition of theacid is regulated by a pH. Though the pH varies depending upon the acidintensity pKa of the dicarboxylic acid, it is at least not more than thepKa. The regulation is preferably operated at a pH of less than 4. Onthe other hand, even when the acid is excessively added, the decrease ofthe pH becomes blunt step-by-step, the excessive salt does not achievesalt exchange with the dicarboxylic acid salt and exists within thesystem. The surplus acid is finally recovered as the raffinate phase inthe subsequently extraction step, and a neutralization treatment or thelike is again required for that treatment, and hence, such isinefficient. In consequence, the pH is preferably controlled to 1 ormore.

[II. Extract Phase Concentration Step]

In general, since the dicarboxylic acid concentration in the extractionphase is thin, a concentration operation is required. Though a degree ofconcentration is not particularly limited, it is preferable that asolubility of the dicarboxylic acid in the final concentrated liquid isnot more than a saturated solubility and is close to the saturatedsolubility as far as possible.

In addition, the solvent which is used for the extraction frequentlyforms a minimum azeotropic composition together with water, and theazeotropic composition is frequently a composition in which a ratio ofthe solvent is larger than that of water. In consequence, a large amountof the solvent is distilled off following the concentration operation,and the solvent concentration in the concentrated liquid often decreasesas compared with that before the concentration.

In general, the dicarboxylic acid obtained from a raw material derivedfrom biomass resources contains a large amount of impurities which arehighly soluble in water, and hence, in the subsequent crystallizationstep, a purification effect in which the system where water exists ishigher than the system where the solvent coexists can be expected. Inaddition, when the solvent remains until the subsequent step, itsrecovery becomes more difficult, and therefore, the solventconcentration after the concentration is not more than 1%.

In order that the solvent concentration of the final concentrated liquidmay be not more than 1% and made close to the saturated solubility, itis preferable to add water before the concentration and/or in theprocess of the concentration operation.

[III. Crystallization Step]

In general, the crystallization step is a step of crystallizing thedicarboxylic acid in the solution containing an extract phase as a soliddicarboxylic acid while utilizing a difference in solubility of thedicarboxylic acid or the like. Any method may be adopted so far as it isa step of crystallizing the dicarboxylic acid as a solid from thesolution containing an extract phase.

More specifically, examples thereof include a cooling crystallizationmethod of achieving crystallization utilizing temperature dependency ofthe solubility by varying the solution temperature; a method ofachieving crystallization by volatilizing the solvent from the solutionby an operation such as heating, pressure reduction, etc. to increasethe dicarboxylic acid concentration in the solution; a method composedof a combination thereof; and the like.

In addition, in the cooling crystallization, examples of a coolingmethod thereof include a method of achieving cooling by circulating thesolution containing an extract phase into an external heat exchanger,etc.; a method of throwing a tube through which a coolant circulatesinto the solution containing an extract phase; and the like.

Above all, according to a method in which the solvent in the solution isvolatilized by decompressing the inside of the apparatus, therebyachieving cooling by evaporation heat of the solvent, not only hindranceof heat transfer to be caused due to deposition of the dicarboxylic acidon a heat exchange interface can be prevented, but concentration of thedicarboxylic acid in the solution follows, and this method is alsopreferable from the standpoint of crystallization yield.

In addition, the crystallization operation may be either a batchoperation or a continuous operation. However, the continuous operationis preferable for reasons such that a scatter in particle size of theresulting solid dicarboxylic acid can be minimized; the operation isefficient for the mass production; and the energy required for thecrystallization can be minimized; and other reason. A crystallizationapparatus is not required to be a special crystallization tank, andknown mixing tanks can be used.

[IV. Solid-Liquid Separation Step]

A dicarboxylic acid slurry obtained by crystallization is subjected to asolid-liquid separation operation, thereby separating a dicarboxylicacid crystal and a mother liquid from each other. A separation method isnot particularly limited, and examples thereof include filtrationseparation, settling separation, and the like. In addition, theoperation may be either a batch manner or a continuous manner. Forexample, examples of a solid-liquid separator with good efficiencyinclude a continuous centrifugal filter, a centrifugal settler such asdecanter, etc., and the like.

In addition, a wet cake recovered by the solid-liquid separationoperation depending upon a required purity of the dicarboxylic acid canbe rinsed with cold water or the like.

[V. Crystallization Mother Liquid Recycling Step]

At least a part of the mother liquid and/or rinsed liquid obtained inthe solid-liquid separation step can be recycled into the step beforethe crystallization step. Though the step to be recycled is notparticularly limited, recycling can be made into the extraction step orthe concentration step.

When recycling is made into the extraction step, though an extractioncolumn becomes large, impurities which are liable to be distributed intothe water phase (with a small distribution coefficient) can beselectively removed from the recycling system. On the other hand, whenrecycling is made into the concentration step, though an extractioncolumn may be made small, all of non-volatile impurities are accumulatedwithin the recycling system.

Though all of the mother liquid and the rinse liquid can be recycled, inview of the fact that when the operation is continued for a long periodof time, the impurities are accumulated within the recycling system, itis preferable to purge at least a part thereof out the system. Ingeneral, the purged water is disposed after treating the organicmaterial with an activated sludge or the like. However, since the purgedwater contains the dicarboxylic acid and has a low pH, it is effectiveas a deactivating agent of the used bacterial cell as recovered by thefermentation operation.

As to the recycling, a recycling amount and a recycling place can bedetermined depending upon the required specification of the dicarboxylicacid.

[Other Purification Steps]

There may be the case where the dicarboxylic acid obtained by theforegoing methods is required to be further applied to a purificationtreatment or a drying step. That is, in the purification from thefermentation liquid containing a dicarboxylic acid, in many cases, it isimportant to decrease the amounts of, in addition to the nitrogenelement contained in the biomass resources, many impurities such as anitrogen element and ammonia derived from fermentation microorganisms,sulfur-containing impurities, metal cations, etc. In addition, there maybe the case where it is necessary to reduce the content of a coloringcomponent or an odorous component contained in the dicarboxylic acid, orto reduce the amount of impurities displaying absorption in anultraviolet ray region of from 250 to 300 nm to an extent that anaverage absorbance is not more than 0.05.

Examples of such a removal method of impurities include treatments suchas a decoloration step with an adsorbing agent such as an activatedcarbon, etc., an ion exchange step of removing coexistent ions with anion exchange resin, a hydrogen treatment step for the purpose ofhydrogenation of an existent unsaturated dicarboxylic acid, acrystallization step of further achieving high-degree purification, etc.

In addition, examples of a removal method of an odorous componentinclude a deodorization method with an adsorbing agent such as anactivated carbon, etc., a cleansing removal method with an organicsolvent, a crystallization method, an aeration method, and the like. Asother means, a hydrogen treatment in the presence of a catalyst iseffective.

Of these deodorization methods of a dicarboxylic acid, for example, inthe case of containing succinic acid as the component derived frombiomass resources, there may be the case where the dicarboxylicacid-containing liquid contains a small amount of fumaric acid.Therefore, when a hydrogen treatment is carried out, not only theodorous component in the dicarboxylic acid can be easily removed, butsuccinic acid is formed from fumaric acid, and an enhancement of theyield of succinic is simultaneously achieved. Thus, the hydrogentreatment method is an especially excellent technique.

In addition, in order to reduce the amount of impurities displayingabsorption in an ultraviolet ray region of from 250 to 300 nm to anextent that the average absorbance is not more than 0.05, a technique inwhich an aliphatic dicarboxylic acid is subjected to a hydrogentreatment, and a purification treatment such as a crystallizationtreatment, an activated carbon treatment, etc. is further combinedtherewith and achieved is effective.

Embodiments of the respective steps are hereunder described in detail byreference to the case where the dicarboxylic acid is succinic acid. But,these descriptions are representative examples of the embodiments, andit should not be construed that the present invention is limitedthereto.

The hydrogen treatment may be any reaction form of a batch system or acontinuous system and can be carried out according to the conventionallyknown method. Specifically, examples of the hydrogen treatment include amethod in which a solution containing succinic acid and a hydrogenationcatalyst are allowed to coexist in a pressure reactor, this mixture issubjected to a hydrogen treatment by introducing a hydrogen gasthereinto while stirring, and a succinic acid-containing reaction liquidafter the treatment is separated from the hydrogenation catalyst anddischarged from the reactor; a method in which using a fixed bedmultipipe type or single pipe reactor, a succinic acid-containingsolution and a hydrogen gas are subjected to a hydrogen treatment whilecirculating them from a lower part of the reactor, and a succinicacid-containing reaction liquid after the treatment is discharged; amethod in which a hydrogen gas is circulated from a lower part of areactor, and a succinic acid-containing solution is circulated from anupper part thereof, thereby carrying out a hydrogen treatment, and asuccinic acid-containing reaction liquid after the treatment isdischarged; and the like.

As the hydrogenation catalyst, known homogenous or heterogeneous noblemetal-containing hydrogenation catalysts can be used. Though thehydrogenation catalyst is not particularly limited, specific examplesthereof include hydrogenation catalysts containing a noble metal such asruthenium, rhodium, palladium, platinum, etc. Of these, hydrogenationcatalysts containing palladium or platinum are preferable, and inparticular, hydrogenation catalysts containing palladium are morepreferable.

In such a hydrogenation catalyst, the foregoing noble metal-containingcompound can be used as it is, or can be used while allowing a ligandsuch as organic phosphines, etc. to coexist. However, heterogeneousnoble metal-containing catalysts are preferable from a reason ofeasiness of catalyst separation.

In addition, such a noble metal-containing compound is able to achievethe hydrogen treatment in the copresence of silica or titanium, a metaloxide such as zirconia, active alumina, etc., or a composite metal oxidethereof, or an activated carbon. This method is a preferred embodimentbecause not only the odorous component contained in succinic acidderived from biomass resources but the coloring component or organicimpurities can be simultaneously adsorbed and removed, and theimpurities can be efficiently removed.

The same effects can also be achieved at the time of using a catalystobtained by supporting the foregoing noble metal on a carrier such assilica or titanium, a metal oxide, for example, zirconia, activealumina, etc., or a composite metal oxide thereof, or an activatedcarbon, and therefore, a method of using such a supported catalyst isalso suitably adopted.

In general, a supporting amount of the noble metal is preferably from0.1 to 10% by weight of the carrier. In addition, though the carrier isnot particularly limited, for a reason that an elution amount of themetal during the hydrogen treatment is small, silica or an activatedcarbon is preferable, and an activated carbon is especially preferable.

In consequence, the embodiment in which the hydrogen treatment iscarried out with a hydrogenation catalyst obtained by supporting theforegoing noble metal on a carrier such as silica or titanium, a metaloxide, for example, zirconia, active alumina, etc., or a composite metaloxide thereof, or an activated carbon is included in the definition ofan embodiment in which the hydrogenation treatment is carried out with ahydrogenation catalyst in the presence of any one adsorbing agentselected from the group consisting of a metal oxide, silica, and anactivated carbon.

Examples of the solvent into which the component derived from biomassresources is incorporated at the time of the hydrogen treatment includewater; organic acids such as acetic acid, propionic acid, etc.; esterssuch as ethyl acetate, etc.; alcohols such as methanol, ethanol,propanol, isopropanol, butanol, 2-ethyl-1-hexanol, isobutanol, etc.;ethers such as diethyl ether, di-n-butyl ether, diisopropyl ether,di-n-butyl ether, tetrahydrofuran, dioxane, etc.; ketones such asacetone, methyl ethyl ketone, diethyl ketone, etc.; nitriles such asacetonitrile, etc.; mixed solvents thereof; and the like. Of these,water is the most preferable.

In general, the water is preferably deionized water, distilled water,river water, well water, tap water, or the like. The solution obtainedby crystallizing succinic acid from the succinic acid-containingreaction liquid in a post step after the hydrogenation reaction,followed by filtration can also be repeatedly used according to theneed. A succinic acid concentration in the solution may be not more thanthe saturated solubility at the liquid temperature.

In general, as to a content of fumaric acid that is an unsaturateddicarboxylic acid contained in succinic acid to be subjected to thehydrogen treatment, a lower limit thereof is preferably 0.01% by weightor more, and more preferably 0.05% by weight or more, and an upper limitthereof is preferably not more than 10% by weight, and more preferablynot more than 5% by weight relative to the weight of succinic acid. Whenthe content of fumaric acid is 0.01% by weight or more, the matter thatthe purification process until the hydrogen treatment step becomescomplicated can be prevented. On the other hand, when the content offumaric acid is not more than 10% by weight, the matter that it takes along time for the hydrogen treatment can be prevented, and such aproblem that a high-concentration succinic acid solution cannot beprepared while suppressing the deposition of fumaric acid having a lowsolubility can be prevented.

Though the hydrogen to be used may be pure hydrogen, hydrogen dilutedwith an inert gas such as nitrogen, helium, argon, etc. can also beused. In general, a concentration of carbon monoxide in the hydrogen gasis preferably not more than 10,000 ppm, more preferably not more than2,000 ppm, and still more preferably not more than 1,000 ppm because theinfluence against the hydrogen treatment efficiency is a matter ofconcern.

As to a hydrogen pressure at the time of the hydrogen treatment, ingeneral, a lower limit thereof is preferably 0.1 MPa or more, and ingeneral, an upper limit thereof is preferably not more than 5 MPa, morepreferably not more than 3 MPa, and still more preferably not more than1 MPa. When the hydrogen pressure is 0.1 MPa or more, the reaction rateincreases, so that the matter that it takes a time too much untilcompletion of the reaction can be prevented. On the other hand, when thehydrogen pressure is not more than 5 MPa, it is possible to prevent theformation of, as a by-product, a hydride of succinic acid such asbutanediol, tetrahydrofuran, etc. depending upon the catalyst orreaction condition.

As to a temperature at the time of the hydrogen treatment, in general, alower limit thereof is preferably 30° C. or higher, and more preferably50° C. or higher, and in general, an upper limit thereof is preferablynot higher than 150° C., and more preferably not higher than 120° C.When the reaction temperature is 30° C. or higher, the reaction rateincreases, so that the matter that it takes a time too much untilcompletion of the reaction can be prevented. On the other hand, when thereaction temperature is not higher than 150° C., not only the formationof, as a by-product, a hydride of succinic acid can be prevented, butthe matter that the amount of a by-product such as malic acid, etc.increases at the time of using water as the solvent can be prevented.

Examples of the crystallization solvent in the crystallization treatmentinclude water; organic acids such as acetic acid, propionic acid, etc.;esters such as ethyl acetate, etc.; alcohols such as methanol, ethanol,propanol, isopropanol, butanol, 2-ethyl-1-hexanol, isobutanol, etc.;ethers such as diethyl ether, di-n-butyl ether, diisopropyl ether,di-n-butyl ether, tetrahydrofuran, dioxane, etc.; ketones such asacetone, methyl ethyl ketone, diethyl ketone, etc.; nitriles such asacetonitrile, etc.; mixed solvents thereof; and the like. Of these,water is the most preferable. In general, the water is preferablydeionized water, distilled water, river water, well water, tap water, orthe like.

A crystallization temperature can be chosen from the range of preferablyfrom about 0 to 90° C., and more preferably from about 0 to 85° C. Acooling rate can be chosen within the range of preferably from about 1to 120° C./hr, and more preferably from about 5 to 60° C./hr, and it ispreferable to conduct the crystallization at ordinary pressure (forexample, about 1 atm.), under reduced pressure, or under elevatedpressure. In addition, an aging time can be suitably chosen within therange of preferably from about 0.1 to 5 hours, more preferably fromabout 0.5 to 4 hours, and still more preferably from about 0.5 to 2hours.

By combining the foregoing crystallization treatment with an activatedcarbon treatment according to the need, the amount of impuritiescontained in succinic acid, which display absorption in an ultravioletray region of from 250 to 300 nm, may be reduced to an extent that anaverage absorbance is not more than 0.05.

As the activated carbon to be used, arbitrary known activated carbonsincluding coal based, wood based, coconut shell based, or resin basedactivated carbons or the like are useful. In addition, activated carbonsobtained by activating each of these various raw material activatedcarbons including coal based, wood based, coconut shell based, or resinbased activated carbons or the like through a method such as a gasactivation method, a steam activation method, a chemical activationmethod using zinc chloride, phosphoric acid, or the like, etc. areuseful.

Specific examples thereof include Calgon CPG, Calgon CAL, Calgon SGL,Diasorb W, Diahope MS10, Diahope MO10, Diahope MS16, Diahope 6MD,Diahope 6MW, Diahope 8ED, Diahope ZGN4, and Centur, all of which aremanufactured by Calgon Mitsubishi Chemical Corporation; GAC, GAC PLUS,GCN PLUS, C GRAN, RO, ROX, DARCO, CN, SX, SX PLUS, SA, SX, PK, and W,all of which are manufactured by Norit Japan Co., Ltd.; GW, GWH, GLC,4GC, KW, PW, and PK, all of which are manufactured by Kuraray ChemicalCo., Ltd.; HC-305, GL-30S, 4G-3S, PA, and PC, all of which aremanufactured by Tsurumi Coal Co., Ltd.; P, W, CW, SG, SGP, S, GB, CA,and K, all of which are manufactured by Futamura Chemical Co., Ltd.;Shirasagi KL, Shirasagi W2C, Shirasagi WH2C, Shirasagi WSC, ShirasagiWHSC, Shirasagi WHSX, Shirasagi XS7100H-3, Carboraffin, Shirasagi A,Shirasagi C, and Shirasagi M, all of which are manufactured by JapanEnviroChemicals, Ltd.; Hokuetsu CL-K, Hokuetsu HS, and Hokuetsu KS, allof which are manufactured by Ajinomoto Fine-Techno Co., Inc.; and thelike.

Of these, a coconut shell based activated carbon and a wood basedactivated carbon are preferable for the reason that they are able toefficiently remove impurities contained in an aliphatic dicarboxylicacid, especially succinic acid, which display absorption in anultraviolet ray region of from 250 to 300 nm.

On the other hand, from the viewpoint of efficiently removing a coloringcomponent of an aliphatic dicarboxylic acid, especially succinic acid,an activated carbon activated by a gas activation method, a steamactivation method, a chemical activation method using zinc chloride,phosphoric acid, etc., or other method is preferable. Of these, anactivated carbon activated by a steam activation method or a chemicalactivation method using zinc chloride, phosphoric acid, etc. ispreferable; and an activated carbon activated by a chemical activationmethod using zinc chloride, phosphoric acid, etc. is especiallypreferable.

As to the shape of the activated carbon to be used, any of a poweredactivated carbon, a crushed activated carbon, a molded activated carbon,or a fibrous activated carbon is useful. In the case where the activatedcarbon is used upon being packed in a column, a particulate or granularactivated carbon is preferable in view of controlling a column pressure.

As a system for the activated carbon treatment, any of a method ofmixing the activated carbon in a batch manner and then subjecting themixture to filtration separation, or a method of allowing the liquid toflow into a packed layer of the activated carbon is adoptable. Ingeneral, a treatment time is preferably from 5 minutes to 5 hours, andmore preferably from 10 minutes to 2 hours in the case of a batchmanner, and in general, it is preferably from 0.1 to 20 hr⁻¹ in terms ofSV (space velocity) in the case of a packed column system. In general, atreatment temperature is preferably from 20 to 90° C.

Furthermore, for the purpose of removing impurities in succinic acid, apurification operation such as an ion exchange column treatment, etc.may be adopted in combination. The ion exchange column treatment asreferred to herein is to allow the liquid to be treated to flow into acolumn packed with an ion exchange resin, thereby removing an ion.

The ion exchange resin should be selected depending upon an ioncontained in the liquid to be treated and the purity of succinic acid asrequired. For example, for the purpose of removing an anion such as asulfate ion, a chlorine ion, etc., an anion exchange resin (OH type) canbe used; and for the purpose of removing a cation such as a metal ion,an ammonium ion, etc., a cation exchange resin (H type) can be used. Theboth may be used according to the need.

The ion exchange resin is classified into a strongly acidic cationexchange resin, a weakly acidic cation exchange resin, a strongly basicanion exchange resin, and a weakly basic anion exchange resin dependingupon the intensity of an acid or base of a functional group thereof.Furthermore, the ion exchange resin is classified into a gel type and aporous type depending upon the shape thereof, but the ion exchange resinto be used is not particularly limited. However, taking intoconsideration the efficiency of ion exchange, it is preferable to use astrongly acidic cation exchange resin with a higher intensity as theacid or a strongly basic anion exchange resin with a higher intensity asthe base. In addition, there is no special reason that the shape is aporous type, and it is preferable to use a gel type which is generallyuseful and inexpensive. Specifically, there are exemplified Diaion SK1B(H type), etc. for the cation exchange resin and Diaion SA10A, etc. forthe anion exchange resin, respectively.

The ion exchange column treatment can be carried out within thetemperature range of a temperature at which succinic acid is dissolvedin a liquid to be treated or higher and lower than a heat-resistanttemperature of the ion exchange resin. That is, in the cation exchangeresin, in general, the treatment is preferably carried out at from 20 to100° C., the temperature of which, however, varies depending upon theconcentration of succinic acid in a liquid to be treated. On the otherhand, the anion exchange resin is lower in heat resistance than thecation exchange resin, and therefore, in general, the treatment ispreferably carried out at from 10 to 80° C. From the viewpoint of thetreatment temperature, in the case of using the anion exchange columntreatment, a step in which the column treatment can be achieved in a lowconcentration of succinic acid at a low temperature is preferable.

In addition, though the method of allowing the liquid to flow is notparticularly limited, in general, the treatment is preferably carriedout at a space velocity (SV) of from 0.1 to 10 hr⁻¹ and at a superficialvelocity of from 1 to 20 m/hr. When the treatment rate is not more thanthe upper limit, the matter that a pressure loss becomes large beforeand after the column is prevented, and the ion exchange becomessufficient. In addition, when the treatment rate is the lower limit ormore, the matter that the column becomes unnecessarily large can beprevented.

In general, in the column treatment, when the ion concentration isalways or periodically measured in a column outlet, and leakage of theion in the column outlet is found, the ion exchange resin is subjectedto a regeneration treatment. The regeneration of the ion exchange resincan be carried out using an acid such as sulfuric acid, hydrochloricacid, etc. in the cation exchange resin or an alkali such as causticsoda, etc. in the anion exchange resin, respectively according to ausual method.

At the time of using the resulting dicarboxylic acid as a polymer rawmaterial, there may be the case where it is necessary to reduce theamount of impurities displaying absorption in an ultraviolet ray regionof from 250 to 300 nm such that an average absorbance is not more than0.05. In that case, the average absorbance is preferably not more than0.03, and especially preferably not more than 0.01. When an aliphaticdicarboxylic acid having a high average absorbance is used as a polymerraw material, there may be the case where coloration of the producedpolymer becomes remarkable.

In the case where the aliphatic dicarboxylic acid is succinic acid, theabsorbance in the present description is a value obtained by charging a3.0 wt % succinic acid aqueous solution in a quartz cell having anoptical path length of 1 cm and achieving the measurement by anultraviolet-visible absorption spectrophotometer. In the presentdescription, though the absorbance was measured using anultraviolet-visible absorption spectrophotometer (Hitachi'sspectrophotometer: UV-3500), it can also be measured using acommercially available ultraviolet-visible absorption spectrophotometer.

The absorbance (A) as referred to herein is an absorbance when measuredat an optical path length 1 cm and is a value calculated according tothe following definition.A=log₁₀(I ₀ /I)

(Here, I₀ represents an intensity of incident light; and I represents anintensity of transmitted light.)

In addition, the average absorbance in an ultraviolet ray region of from250 to 300 nm is a value obtained by dividing the total sum ofabsorbances measured at intervals of 1 nm within the range of from 250to 300 nm by 51.Average absorbance=(Total sum of absorbances measured at intervals of 1nm within the range of from 250 to 300 nm)/51

In the present description, though the foregoing impurities displayingabsorption in an ultraviolet ray region of from 250 to 300 nm are notparticularly limited, examples thereof include compounds having anitrogen element and compounds displaying aromaticity. Examples of suchcompounds include oxygen-containing heterocyclic aromatic compounds suchas furan, etc.; nitrogen-containing heterocyclic aromatic compounds suchas pyrrole, pyridine, pyrazine, etc.; and benzene based aromaticcompounds such as phenol, benzaldehyde, benzoic acid, etc.

Specific examples thereof include monohydroxybenzoic acids such asfurfural, furfuryl alcohol, methylfurfuryl alcohol,hydroxymethylfurfural, furosine, 2-pyrrolecarboxyaldehyde,pyrrolecarboxylic acid, methylpyrrolecarboxylic acid, pyridinecarboxylicacid, pyridinedicarboxylic acid, methylpyridinecarboxylic acid,methylpyridinedicarboxylic acid, pyrazine, 2-methylpyrazine,dimethylpyrazine, trimethylpyrazine, tetramethylpyrazine, phenol,benzoic acid, salicylic acid, creosotic acid, etc.; dihydroxybenzoicacids such as pyrocatechuic acid, protocatechuic acid, etc.;trihydroxybenzoic acids such as gallic acid, etc.; aromatic aldehydessuch as benzaldehyde, methyl benzaldehyde, dimethyl benzaldehyde, etc.;mixtures thereof; and the like. Incidentally, while there may be thecase where the foregoing compounds include isomers, the foregoingexamples of the compounds include all of isomers.

As described previously, the species of impurities to be removed varydepending upon the kind of the activated carbon, and therefore, examplesof a method for removing such impurities include a method of combiningplural species of activated carbon and a method of combining anactivated carbon treatment with the foregoing hydrogen treatment orcrystallization treatment. In addition, at the time of using water asthe solvent, there may be the case where a water-insoluble componentincorporates into the dicarboxylic acid solution derived from thefermentation. Such incorporation of an insoluble component causes alowering in the efficiency of the foregoing removal of impurities by anactivated carbon or the subsequent purification step, and therefore, itis preferable to remove the insoluble component in advance.

A method in which the removal of an insoluble component is carried outby subjecting the succinic acid solution derived from the fermentationto a known membrane permeation treatment in a step after deriving intosuccinic acid from a succinate formed by the fermentation method untilthe activated carbon treatment step is preferable. Also, as anothermethod, a method in which permeability of the membrane permeationtreatment is enhanced by adsorbing the insoluble component in thecopresence of a powdered activated carbon, or a method in which theforegoing impurities are simultaneously adsorbed and removed togetherwith the insoluble component using an appropriate powdered active carbonis also suitably adopted.

Furthermore, at the time of carrying out the removal of impurities bymeans of a combination of crystallization or/and an activated carbontreatment with a hydrogen treatment, though there are no particularlimitations, a process of carrying out the crystallization or/and theactivated carbon treatment step before the hydrogen treatment step issuitably adopted because the impurities are efficiently removed. Thisprocess is also suitably adopted in the removal of impurities from thesuccinic acid solution derived from biomass resources.

The succinic acid recovered by means of crystallization can be dried inthe usual way depending upon its application. In general, the succinicacid is dried to such an extent that its water content is preferablyfrom 0.1 to 2% by weight, and more preferably from 0.2 to 1% by weight.

The drying method is not particularly limited, and a direct heatingsystem for directly heating it with warm air, an indirect heating systemwith a steam, or the like is adoptable depending upon the heating type.For example, a box type dryer, a band dryer, a rotary dryer, and thelike are exemplified as the dryer with warm air; a drum dryer, a discdryer, and the like are exemplified as the dryer by means of indirectheating.

In addition, the operation pressure may be ordinary pressure or reducedpressure. Furthermore, the operation system may be either a batchoperation or a continuous operation. In general, the temperature of warmair is preferably from 20 to 200° C., and more preferably from 50 to150° C. in terms of a temperature of the heating plane. When thetemperature is 20° C. or higher, the matter that a highly reducedpressure is required for drying can be prevented. In addition, when thetemperature is not more than 200° C., the matter that succinic acid isdehydrated to form succinic anhydride can be prevented.

In addition, the dicarboxylic acid can also be purified to the sameextent by a method described below. A purification method of the casewhere the dicarboxylic acid is succinic acid is hereunder described asan example.

That is, a technique for carrying out a reactive crystallization step ofnot only forming succinic acid but depositing the formed succinic acidin the copresence of an alcohol by a multi-stage manner by reactingammonium succinate as fermentation-produced with a microorganism or asolution thereof with a monocarboxylic acid is also effective. Thoughthe monocarboxylic acid to be used is not particularly limited so far asit is a monocarboxylic acid capable of converting ammonium succinateinto succinic acid, it is preferably acetic acid or propionic acid.

In addition, what the reactive crystallization step is carried out by amulti-stage manner means that after adding a monocarboxylic acid to theammonium succinate reaction liquid to carry out first-stage reactivecrystallization, an ammonium succinate intermediate deposited by thefirst-stage reactive crystallization, such as monoammonium succinate,etc., is separated; a monocarboxylic acid is newly added to theseparated intermediate to carry out second-stage reactivecrystallization; and the separation of an intermediate and the reactivecrystallization with a monocarboxylic acid are repeated according to theneed. Such multi-stage reactive crystallization is especially effectivefor the case where the amount of impurities is large, the case wheresuccinic acid in the mother liquid is recovered by means ofrecrystallization, or the like.

The term “multi-stage” means two or more stages, and preferably from twoto four stages. However, what number of stages should the reactivecrystallization be carried out in total can be arbitrarily set accordingto the reaction scale, the required purity, or the like. As to thematter that at what number of final stage is obtainable free succinicacid by carrying out the reactive crystallization, it is preferable toset a total number of stages in advance by carrying out a preliminaryexperiment, or the like.

As the specific crystallization apparatus which is used for the reactivecrystallization step, in addition to a mixing tank, generally usedcrystallization tanks can be used. The apparatus is unconcerned aboutits shape or technique so far as a crystal can be obtained by asolid-liquid equilibrium phenomenon. Examples thereof include aKrystal-Oslo crystallizer, a draft tube bulb crystallizer, a mixing tankcrystallizer, a Swenson crystallizer, and the like.

The reactive crystallization condition is different between the finalstage and other stage (preceding stage). First of all, the condition ofthe preceding stage is described. That is, in the preceding stage, sinceit is intended to convert diammonium succinate into monoammoniumsuccinate as far as possible, it is preferable that the amount of themonocarboxylic acid to be added is equal to or more than the mole ofammonium succinate. However, when the amount of the monocarboxylic acidto be added is excessively large, the recovery rate is lowered due to asolvent effect of the monocarboxylic acid, and therefore, it ispreferably not more than 5 molar times. Incidentally, an optimum valueincreases or decreases depending upon the amount of coexisting ammoniaor water.

In the case of using acetic acid, an upper limit of the acetic acidamount is dominated by the solubility, and this is conspicuouslydependent upon the temperature. Furthermore, in a region having a highpH, the viscosity is high, and it takes a long time for the filtration,and therefore, a weight ratio of ammonia and acetic acid is much morepreferably 14 or more. On the other hand, when a large amount of aceticacid is used, energy is required for recovery, and therefore, the weightratio of ammonia and acetic acid is preferably not more than 100, andmuch more preferably not more than 30. In the case where propionic acidis used, a lower limit of the pH is larger than that of acetic acid.Since an upper limit of the pH is determined by an equilibrium relationwith the salt exchange reaction and solubility, it is equal to that inacetic acid. In consequence, a narrower range than that in acetic acidis the condition.

Though the condition of the temperature or pressure in the precedingstage is not particularly limited, there may be the case where it isrestricted by the kind and amount of the alcohol or monocarboxylic acidto be used, or the crystallization apparatus. For example, in the casewhere a large amount of methanol is used, methanol vaporizes in vacuoand is not aggregated, thereby making the recovery difficult. Thus, itis preferable that the system is not made in vacuo.

In addition, even when a little pressure is kept, there may be the casewhere a refrigerator is necessary. Thus, though the condition variesdepending upon the crystallization apparatus to be used, for example,the temperature is preferably from 0° C. to 50° C., and the pressure ispreferably not more than ordinary pressure and 5 kPa or more.

Though the foregoing reactive crystallization is carried out in thecopresence of an alcohol, the alcohol to be made coexistent ispreferably a monohydric alcohol. In addition, an alcohol having a carbonnumber of from 1 to 3 is preferable. In particular, methanol, ethanol,1-propanol, and 2-propanol are preferable.

The alcohol is added in the preceding stage, and its addition amount ispreferably 5% by weight or more and not more than 40% by weight relativeto the total weight of the ammonium succinate reaction liquid and themonocarboxylic acid. When the alcohol is coexistent, the viscosity of amixture of ammonium succinate and acetic acid decreases, and therefore,the efficiency of the reactive crystallization increases. In addition,in the case where the ammonium succinate solution is mixed with a sugar,there is brought an effect for separating the sugar as in the case offermentation producing the ammonium succinate solution with amicroorganism.

In the light of the above, in the preceding stage, after the alcohol isadded to carry out the reactive crystallization, ammonium succinate isrecovered, and in the final stage, a monocarboxylic acid is added whileregulating the alcohol concentration of the reaction system within therange of from 0.1 ppm to 10%, thereby carrying out the reactivecrystallization. In the final stage, it is preferable to carry out thereactive crystallization without adding an alcohol.

In addition, even in the case where an alcohol is not added, since aconsiderable amount of the alcohol is present in a slurry containingammonium succinate which comes out from the crystallization tank justbefore the final stage, for the purpose of regulating the alcoholconcentration in the reactive crystallization tank of the final stagewithin the range of from 0.1 ppm to 10%, it is preferable to remove thealcohol in the slurry by means of filtration, drying, washing, etc. ofthis slurry.

In addition, the system of the reaction system may contain water.However, in this case, it is also preferable to regulate the waterconcentration in the final-stage reactive crystallization tank to notmore than 10%. In consequence, it is preferable to simultaneously removethe alcohol and water in the slurry by means of filtration, drying,washing, etc. of the ammonium succinate-containing slurry as obtained inthe crystallization tank in the stage just before the final stage.

As a method for removing the alcohol and water from the ammoniumsuccinate-containing slurry as obtained by the preceding stage, forexample, the slurry from the crystallization tank of the preceding stageis subjected to a combination of separation of the mother liquid byusual filtration or centrifugation (centrifugal decantation) or thelike, washing or rinsing with acetic acid or a filtrate (mother liquid)in the final stage, drying or distillation of the solution, and thelike, whereby water or the alcohol can be separated. In addition, thealcohol or water may be removed through a treatment such as centrifugalfiltration, filter pressing, etc.

By obtaining a crystal or concentrated liquid containing succinic acidfrom the slurry obtained in the preceding stage and further carrying outfinal-stage crystallization with acetic acid by an arbitrary method,succinic acid is obtained. As to a final-stage crystallizationcondition, it is preferable that the amount of the alcohol is in therange of from 1 ppm to 10%, and the amount of water is in the range offrom 1 ppm to 10%; and it is much more preferable that the amount ofeach of water and the alcohol is not more than 5%. At that time, the pHobtained from succinic acid is in general from about 2.1 (dissolvedstate) to about 4.5 (filtrate). This is corresponding to the weightratio of ammonia and acetic acid of 13.4 or more.

Furthermore, when the weight ratio of ammonia and acetic acid is 1/14 ormore, the matter that it takes a long time for the filtration can beprevented, and therefore, the weight ratio of ammonia and acetic acid ismuch more preferably 1/14 or more. On the other hand, by using a largeamount of acetic acid, the matter that energy is required for therecovery is prevented, and therefore, the weight ratio of ammonia andacetic acid is preferably not more than 1/100, much more preferably notmore than 1/50, and especially preferably not more than 1/30.

The lower the temperature, the higher the recovery rate is. In a regionwhere the pH is close to 2.1, the melting point of acetic acid that is16° C. is a lower limit value thereof; whereas an upper limit thereof isdominated by the solubility, and in general, it is preferably not higherthan 40° C., and more preferably 20° C. or higher and not higher than35° C. In a region where the pH is close to 4.5, since there isdepression of freezing point of acetic acid, the temperature ispreferably 10° C. or higher; whereas an upper limit thereof is dominatedby the solubility, and in general, it is preferably not higher than 60°C., and more preferably 15° C. or higher and not higher than 40° C.

Incidentally, the amount of acetic acid which is added in thefinal-stage crystallization is preferably from about 0.8 times to 3.5times in terms of a weight ratio relative to the crystal as obtained inthe preceding stage.

As to this final-stage reactive crystallization, there are no particularrestrictions regarding the apparatus. However, usual crystallizationapparatuses, for example, a Krystal-Oslo crystallizer, a draft tube bulbcrystallizer, a mixing tank crystallizer, a Swenson crystallizer, andthe like, can be used. By subjecting the resulting slurry tosolid-liquid separation adopting a general method such as filtration,centrifugation, etc., succinic acid can be obtained. When the crystal iswashed with cold water and acetic acid, succinic acid with a higherpurity can be obtained.

Succinic acid deposited in the final stage is collected by means ofseparation in the usual way. As the separation method, for example, ausual filtration operation, pressure filtration or filtration underreduced pressure with a Nutsche type filter, centrifugation, and thelike can be adopted. Incidentally, as described above, the mother liquidafter collecting succinic acid in the final stage can be reused forwashing the slurry obtained in the preceding stage. Furthermore, adeionization treatment with a cation exchange resin or the like may becarried out according to the need. The thus obtained crystal of succinicacid can be further subjected to heat drying or drying under reducedpressure according to the need.

The dicarboxylic acid derived from biomass resources contains, as animpurity, a nitrogen atom derived from biomass resources and caused dueto a fermentation treatment and a purification treatment including aneutralization step with an acid.

Specifically, a nitrogen atom derived from an amino acid, a protein, anammonium salt, urea, a microorganism, and the like is contained. Ingeneral, for the purpose of obtaining a practically useful polymer, itis important to control the amount of the organic acid having a pKavalue at 25° C. of not more than 3.7, the nitrogen compound, or themetal cation contained in the dicarboxylic acid by the foregoingpurification method.

As to the organic acid having a pKa value at 25° C. of not more than3.7, which is contained in the dicarboxylic acid derived from biomassresources by the foregoing method, a lower limit value thereof is ingeneral more than 0 ppm, preferably 0.001 ppm or more, more preferably0.01 ppm or more, still more preferably 0.05 ppm or more, especiallypreferably 0.07 ppm or more, and most preferably 0.1 ppm or morerelative to the dicarboxylic acid. An upper limit thereof is in generalnot more than 1,000 ppm, preferably not more than 800 ppm, and morepreferably not more than 600 ppm.

When the amount of the organic acid having a pKa value at 25° C. of notmore than 3.7, which is contained in the dicarboxylic acid is more than1,000 ppm, the viscosity of the polyester polyol as a polyurethane rawmaterial becomes high; the handling operability is deteriorated; and apolyurethane having an abnormally high molecule weight, an abnormallylarge molecular weight distribution, or poor mechanical characteristicssuch as flexibility, elasticity, etc. due to gelation or the like at thetime of polyurethane reaction tends to be formed. In addition, when theamount is too large, a scatter of the content is liable to be caused,and not only physical properties of the resulting polyurethane arevariable, but even in the production step, the stable operation tends tobecome difficult.

In addition, when the amount of the organic acid having a pKa value ismore than 0 ppm, the matter that the purification step of thedicarboxylic acid becomes complicated is prevented, an aspect of whichis thus economically advantageous. Furthermore, when formed into apolyurethane, the mechanical strength tends to be enhanced.

Incidentally, by combining the foregoing fermentation condition with thepurification condition such as extraction, crystallization, etc., itbecomes possible to control the content of the organic acid having a pKavalue at 25° C. of not more than 3.7. In addition, the content of theorganic acid may be regulated by adding an organic acid to thedicarboxylic acid having a small amount of an organic acid. In addition,by undergoing a step for controlling the content of the organic acid toa preferred range, the content of a nitrogen atom or the content of asulfur atom contained in the dicarboxylic acid derived from biomassresources can also be controlled, and in general, a dicarboxylic acidsuitable for obtaining a practically useful polymer can be obtained.

As to a content of the nitrogen atom contained in the dicarboxylic acidderived from biomass resources by the foregoing method, in general, anupper limit thereof is preferably not more than 2,000 ppm, morepreferably not more than 1,000 ppm, still more preferably not more than100 ppm, and most preferably not more than 50 ppm in the dicarboxylicacid in terms of a mass ratio relative to the dicarboxylic acid. Ingeneral, a lower limit thereof is 0.01 ppm or more, and more preferably0.05 ppm or more. For an economical reason of the purification step, thelower limit is still more preferably 0.1 ppm or more, yet still morepreferably 1 ppm or more, and especially preferably 10 ppm or more.

When the content of the nitrogen atom contained in the dicarboxylic acidis not more than the foregoing upper limit, retardation of thepolymerization reaction, an increase of the quantity of terminalcarboxyl groups of the polyester polyol, coloration, partial gelation, alowering of the stability, and the like can be prevented. On the otherhand, when the content of the nitrogen atom contained in thedicarboxylic acid is the foregoing lower limit or more, the matter thatthe purification step becomes complicated is prevented, an aspect ofwhich is thus economically advantageous.

The content of the nitrogen atom is a value measured by a known methodsuch as an elemental analysis method, etc., or a method in which anamino acid or ammonia in a sample is separated under a biological aminoacid separation condition using an amino acid analyzer and subjected toninhydrin coloration, followed by detection.

The use of a dicarboxylic acid having a nitrogen atom content fallingwithin the foregoing range is advantageous for reducing the colorationof the resulting polyurethane and polyester polyol. In addition, thereis also brought an effect for delaying the polymerization reaction ofthe polyurethane and polyester polyol.

In addition, in the case of using a dicarboxylic produced by thefermentation method, there may be the case where a large amount of asulfur atom is contained by the purification treatment including aneutralization step with an acid. Specifically, examples of impuritiescontaining a sulfur atom include sulfuric acid, a sulfate, sulfurousacid, an organic sulfonic acid, an organic sulfonate, and the like.

As to a content of the sulfur atom contained in the dicarboxylic acid,in general, an upper limit thereof is preferably not more than 100 ppm,more preferably not more than 20 ppm, still more preferably not morethan 10 ppm, especially preferably not more than 5 ppm, and mostpreferably not more than 0.5 ppm in the dicarboxylic acid in terms of amass ratio relative to the dicarboxylic acid. On the other hand, ingeneral, a lower limit thereof is 0.001 ppm or more, more preferably0.01 ppm or more, still more preferably 0.05 ppm or more, and especiallypreferably 0.1 ppm or more.

When the content of the sulfur atom contained in the dicarboxylic acidis not more than the foregoing upper limit, delay of the polymerizationreaction, partial gelation of the polyester polyol, an increase of thequantity of carboxyl terminal, a lowering of the stability, and the likecan be prevented. On the other hand, when the content of the sulfur atomcontained in the dicarboxylic acid is the foregoing lower limit or more,the matter that the purification step becomes complicated is prevented,an aspect of which is thus economically advantageous. The content of thesulfur atom is a value measured by a known elemental analysis method.

In the present invention, in using the dicarboxylic acid derived frombiomass resources as obtained by the foregoing method as a polyurethaneraw material, a concentration of oxygen within a tank storing thedicarboxylic acid, which is connected to the polymerization system, maybe controlled to not more than a fixed value. According to this,coloration due to an oxidation reaction of a nitrogen source that is animpurity of the polyurethane can be prevented.

For the purposes of controlling the oxygen concentration and storing theraw material, a tank is in general used. But, an apparatus other thanthe tank is also useful without particular limitations so far as it isable to control the oxygen concentration.

The kind of the storage tank is not specifically limited, and knownmetal-made storage tanks or those in which a lining of glass, a resin,or the like is applied to an inner surface thereof, glass-made orresin-made containers, and the like are useful. From the standpoint ofstrength or the like, metal-made tanks or those in which a lining isapplied are preferably used.

As a material of the metal-made tank, known materials are used.Specifically, examples thereof include carbon steels, ferrite basedstainless steels, martensite based stainless steels such as SUS410,etc., austenite based stainless steels such as SUS310, SUS304, SUS316,etc., clad steels, cast iron, copper, copper alloys, aluminum, Inconel,Hastelloy, titanium, and the like.

As to an oxygen concentration within the storage tank of thedicarboxylic acid, though a lower limit thereof is not particularlylimited, in general, it is preferably 0.00001% or more, and morepreferably 0.01% or more relative to the total volume of the storagetank. On the other hand, an upper limit thereof is preferably not morethan 16%, more preferably not more than 14%, and still more preferablynot more than 12%.

When the oxygen concentration within the storage tank of thedicarboxylic acid is the foregoing lower limit or more, the matter thatthe equipment or control step becomes complicated is prevented, anaspect of which is thus economically advantageous. On the other hand,when the oxygen concentration within the storage tank of thedicarboxylic acid is not more than the foregoing upper limit, colorationof the produced polyurethane can be suppressed.

As to a temperature within the storage tank of the dicarboxylic acid, ingeneral, a lower limit thereof is preferably −50° C. or higher, and morepreferably 0° C. or higher. On the other hand, in general, an upperlimit thereof is preferably not higher than 200° C., more preferably nothigher than 100° C., and still more preferably not higher than 50° C.For the reason that the temperature control is not necessary, a methodof storage at room temperature is the most preferable. When thetemperature is −50° C. or higher, an increase of the storage costs canbe prevented. In addition, when the temperature is not higher than 200°C., concurrence of a dehydration reaction of the carboxylic acid or thelike can be prevented.

As to a humidity within the storage tank of the dicarboxylic acid, ingeneral, a lower limit thereof is preferably 0.0001% or more, morepreferably 0.001% or more, still more preferably 0.01% or more, and mostpreferably 0.1% or more; and an upper limit thereof is preferably notmore than 80%, more preferably not more than 60%, and still morepreferably not more than 40%, relative to the total volume of thestorage tank.

When the humidity within the storage tank of the dicarboxylic acid is0.0001% or more, the matter that the control step becomes complicated isprevented, an aspect of which is thus economically advantageous. Inaddition, when the humidity within the storage tank of the dicarboxylicacid is not more than 80%, attachment of the dicarboxylic acid onto thestorage tank or piping and blocking of the dicarboxylic acid can beprevented, and in the case where the storage tank is made of a metal,corrosion of the tank or the like can be prevented.

In general, a pressure within the storage tank of the dicarboxylic acidis preferably atmospheric pressure (ordinary pressure).

In general, the dicarboxylic acid which is used in the present inventionis preferably one with less coloration. As to the yellow index (YIvalue) of the dicarboxylic acid which is used in the present invention,in general, an upper limit thereof is preferably not more than 50, morepreferably not more than 20, still more preferably not more than 10, yetstill more preferably not more than 6, and especially preferably notmore than 4. On the other hand, though a lower limit thereof is notparticularly limited, in general, it is preferably −20 or more, morepreferably −10 or more, still more preferably −5 or more, especiallypreferably −3 or more, and most preferably −1 or more.

When a dicarboxylic acid having a YI value of not more than 50 is used,coloration of the produced polyurethane can be suppressed. On the otherhand, when a dicarboxylic acid having a YI value of −20 or more is used,it is economically advantageous because not only extremely expensiveinvestment in plant and equipment is not required for the production,but a long production time is not required. In the present description,the YI value is a value measured by a method on the basis of JIS-K7105.

(2) Aliphatic Diol:

The aliphatic diol which is used in the present invention is notparticularly limited so far as it is an aliphatic or alicyclic compoundhaving two OH groups, and examples thereof include aliphatic diols inwhich a lower limit value of the carbon atom number is preferably 2 ormore, and an upper limit value thereof is preferably not more than 10,and more preferably not more than 6.

In addition, the diol unit as referred to herein is one derived from anaromatic diol and/or an aliphatic diol, and known compounds can be used.Of these, the use of an aliphatic diol is preferable.

Specific examples of the aliphatic diol include ethylene glycol,1,3-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol,1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,2-butanediol,1,6-hexanediol, decamethylene glycol, 1,9-nonanediol, 1,4-butanediol,1,4-cyclohexanedimethanol, and the like. These may be used solely or inadmixture of two or more kinds thereof.

Of these, ethylene glycol, 1,4-butanediol, 1,3-propanediol,2-methyl-1,3-propanediol and 3-methyl-1,5-pentanediol are preferable.Above all, ethylene glycol, 1,4-butanediol, and a mixture thereof arepreferable; and one containing, as a main component, 1,4-butanediol or1,4-butanediol is especially preferable.

It is meant by the terms “main component” as referred to herein that ingeneral, the subject component accounts for preferably 50% by mole ormore, more preferably 60% by mole or more, still more preferably 70% bymole or more, and especially preferably 90% by mole or more relative tothe whole of diol units. These diols may be used solely, or may be usedin admixture of two or more kinds thereof.

The diol having a branched structure is especially preferably2-methyl-1,3-propanediol or 3-methyl-1,5-pentanediol.

When a diol having a methylene group between the hydroxyl groups andhaving an even carbon number is used, the mechanical strength of theresulting polyurethane increases, and when a diol having an odd carbonnumber or a branched structure is used, the handling properties of thepolyester polyol are enhanced.

In addition to the above, examples of a diol other than the aliphaticdiol, which may be mixed, include aromatic diols. Though the aromaticdiol is not particularly limited so far as it is an aromatic compoundhaving two OH groups, examples thereof include aromatic diols in which alower limit value of the carbon number is preferably 6 or more, whereasin general, an upper limit value thereof is preferably not more than 15.

Specific examples of the aromatic diol include hydroquinone,1,5-dihydroxynaphthalene, 4,4′-dihydroxydiphenyl,bis(p-hydroxyphenyl)methane, bis(p-hydroxyphenyl)-2,2-propane, and thelike. In the present invention, in general, the content of the aromaticdiol in the total amount of the diols is preferably not more than 30% bymole, more preferably not more than 20% by mole, and still morepreferably not more than 10% by mole.

In addition, a polyether, both ends of which are terminated with ahydroxyl group, may be used in combination with the foregoing aliphaticdiol, or may be used solely. As to the polyether, both ends of which areterminated with a hydroxyl group, in general, a lower limit value of thecarbon number is preferably 4 or more, and more preferably 10 or more,and in general, an upper limit value thereof is preferably not more than1,000, more preferably not more than 200, and still more preferably notmore than 100.

Specific examples of the polyether, both ends of which are terminatedwith a hydroxyl group, include diethylene glycol, triethylene glycol,polyethylene glycol, polypropylene glycol, polytetramethylene glycol,poly-1,3-propanediol, poly-1,6-hexamethylene glycol, and the like. Inaddition, a copolymer polyether between polyethylene glycol andpolypropylene glycol and the like can also be used.

In general, the use amount of such a polyether, both ends of which areterminated with a hydroxyl group, is a calculated amount of preferablynot more than 90% by weight, more preferably not more than 50% byweight, and still more preferably not more than 30% by weight as thecontent in the polyester.

In the present invention, diols derived from biomass resources may beused as such a diol. Specifically, the diol compound may be produceddirectly from carbon sources such as glucose, etc. by the fermentationmethod, or a dicarboxylic acid, a dicarboxylic anhydride, or a cyclicether, as obtained by the fermentation method, may be converted into adiol compound by a chemical reaction.

For example, 1,4-butanediol may be produced by means of chemicalsynthesis of succinic acid, succinic anhydride, a succinic acid ester,maleic acid, maleic anhydride, a maleic acid ester, tetrahydrofuran,γ-butyrolactone, or the like, as obtained by the fermentation method, or1,4-butanediol may be produced from 1,3-butadiene obtained by thefermentation process. Of these, a method of obtaining 1,4-butanediol bymeans of hydrogenation of succinic acid in the presence of a reductioncatalyst is efficient and preferable.

Examples of the catalyst to be used for hydrogenating succinic acidinclude Pd, Ru, Re, Rh, Ni, Cu, and Co, and compounds thereof. Morespecifically, examples thereof include Pd/Ag/Re, Ru/Ni/Co/ZnO, Cu/Znoxide, Cu/Zn/Cr oxide, Ru/Re, Re/C, Ru/Sn, Ru/Pt/Sn, Pt/Re/alkali,Pt/Re, Pd/Co/Re, Cu/Si, Cu/Cr/Mn, ReO/CuO/ZnO, CuO/CrO, Pd/Re, Ni/Co,Pd/CuO/CrO₃, Ru phosphate, Ni/Co, Co/Ru/Mn, Cu/Pd/KOH, and Cu/Cr/Zn. Ofthese, Ru/Sn or Ru/Pt/Sn is preferable from the standpoint of catalyticactivity.

Furthermore, a method of producing a diol compound from biomassresources through a combination of known organic chemical catalyticreactions is also positively adopted. For example, in the case ofutilizing pentose as a biomass resource, a diol such as butanediol, etc.can be easily produced through a combination of known dehydrationreaction and catalytic reaction.

There may be the case where the diol derived from biomass resourcescontains a nitrogen atom as an impurity derived from biomass resourcesor caused due to a fermentation treatment or a purification treatmentincluding a neutralization step with an acid. In that case,specifically, a nitrogen atom derived from an amino acid, a protein,ammonia, urea, or a fermentation microorganism is contained.

As to a content of a nitrogen atom contained in the diol produced by thefermentation method, in general, an upper limit thereof is preferablynot more than 2,000 ppm, more preferably not more than 1,000 ppm, stillmore preferably not more than 100 ppm, and most preferably not more than50 ppm in terms of a mass ratio relative to the diol. Though a lowerlimit thereof is not particularly limited, in general, it is preferably0.01 ppm or more, and more preferably 0.05 ppm or more. For the reasonof economy of the purification step, the lower limit is still morepreferably 0.1 ppm or more, yet still more preferably 1 ppm or more, andespecially preferably 10 ppm or more.

When the content of the nitrogen atom contained in the diol produced bythe fermentation method is not more than the foregoing upper limit,retardation of the polymerization reaction, an increase of the quantityof terminal carboxyl groups of the polyester polyol, coloration, partialgelation, a lowering of the stability, and the like can be prevented. Onthe other hand, when the content of the nitrogen atom contained in thedicarboxylic acid is the foregoing lower limit or more, the matter thatthe purification step becomes complicated is prevented, an aspect ofwhich is thus economically advantageous.

In addition, in another embodiment, as to a content of a nitrogen atomcontained in the dicarboxylic acid raw material and diol, in general, anupper limit thereof is preferably not more than 2,000 ppm, morepreferably not more than 1,000 ppm, still more preferably not more than100 ppm, and most preferably not more than 50 ppm in terms of a massratio relative to a total sum of the foregoing raw materials. Though alower limit thereof is not particularly limited, in general, a lowerlimit thereof is preferably 0.01 ppm or more, more preferably 0.05 ppmor more, and still more preferably 0.1 ppm or more.

In the case of using the diol produced by the fermentation method, theremay be the case where a sulfur atom is contained by the purificationtreatment including a neutralization step with an acid. In that case,specifically, examples of impurities containing a sulfur atom includesulfuric acid, sulfurous acid, an organic sulfonate, and the like.

As to a content of the sulfur atom contained in the diol, in general, anupper limit thereof is preferably not more than 100 ppm, more preferablynot more than 20 ppm, still more preferably not more than 10 ppm,especially preferably not more than 5 ppm, and most preferably not morethan 0.5 ppm in the diol in terms of a mass ratio relative to the diol.On the other hand, though a lower limit thereof is not particularlylimited, in general, it is 0.001 ppm or more, more preferably 0.01 ppmor more, still more preferably 0.05 ppm or more, and especiallypreferably 0.1 ppm or more.

When the content of the sulfur atom contained in the diol is not morethan the foregoing upper limit, retardation of the polymerizationreaction, an increase of the quantity of terminal carboxyl groups of thepolyester polyol, coloration, partial gelation, a lowering of thestability, and the like can be prevented. On the other hand, when thecontent of the nitrogen atom contained in the diol is the foregoinglower limit or more, the matter that the purification step becomescomplicated is prevented, an aspect of which is thus economicallyadvantageous. The content of the sulfur atom is a value measured by aknown elemental analysis method.

In addition, in another embodiment, as to a content of a sulfur atomcontained in the dicarboxylic acid raw material and diol, in general, anupper limit thereof is preferably not more than 100 ppm, more preferablynot more than 20 ppm, still more preferably not more than 10 ppm,specially preferably not more than 5 ppm, and most preferably not morethan 0.5 ppm as reduced into an atom in terms of a mass ratio relativeto a total sum of the foregoing raw materials. Though a lower limitthereof is not particularly limited, in general, a lower limit thereofis preferably 0.001 ppm or more, more preferably 0.01 ppm or more, stillmore preferably 0.05 ppm or more, and especially preferably 0.1 ppm ormore.

In the present invention, in using the diol derived from biomassresources as obtained by the foregoing method as a polyurethane rawmaterial, for the purpose of suppressing coloration of the polyurethaneto be caused due to the foregoing impurities, a concentration of oxygenor a temperature within a tank storing the diol, which is connected tothe polymerization system, may be controlled.

This control makes it possible to suppress the coloration of theimpurities themselves or the oxidation reaction of the diol acceleratedby the impurities. For example, in the case of using 1,4-butanediol,coloration of a polyurethane due to an oxidation product of the diolsuch as 2-(4-hydroxybutyloxy)tetrahydrofuran, etc. can be prevented.

For the purposes of controlling the oxygen concentration and storing theraw material, a tank is in general used. But, an apparatus other thanthe tank is also useful without particular limitations so far as it isable to control the oxygen concentration. The kind of the storage tankis not specifically limited, and known metal-made storage tanks or thosein which a lining of glass, a resin, or the like is applied to an innersurface thereof, glass-made or resin-made containers, and the like areuseful. From the standpoint of strength or the like, metal-made tanks orthose in which a lining is applied are preferably used.

As a material of the metal-made tank, known materials are used.Specifically, examples thereof include carbon steels, ferrite basedstainless steels, martensite based stainless steels such as SUS410,etc., austenite based stainless steels such as SUS310, SUS304, SUS316,etc., clad steels, cast iron, copper, copper alloys, aluminum, Inconel,Hastelloy, titanium, and the like.

As to an oxygen concentration within the storage tank of the diol,though a lower limit thereof is not particularly limited, in general, itis preferably 0.00001% or more, more preferably 0.0001% or more, stillmore preferably 0.001% or more, and most preferably 0.01% or morerelative to the total volume of the storage tank. In general, an upperlimit thereof is preferably not more than 10%, more preferably not morethan 5%, still more preferably not more than 1%, and most preferably notmore than 0.1%.

When the oxygen concentration within the storage tank of the diol is0.00001% or more, the matter that the control step becomes complicatedis prevented, an aspect of which is thus economically advantageous. Inaddition, when the oxygen concentration is not more than 10%, anincrease of coloration of the polymer by an oxidation reaction productof the diol can be prevented.

As to a storage temperature within the storage tank of the diol, ingeneral, a lower limit thereof is preferably 15° C. or higher, morepreferably 30° C. or higher, still more preferably 50° C. or higher, andmost preferably 100° C. or higher; and an upper limit thereof ispreferably not higher than 230° C., more preferably not higher than 200°C., still more preferably not higher than 180° C., and most preferablynot higher than 160° C.

When the storage temperature within the storage tank of the diol is 15°C. or higher, the matter that the it takes a long time for raising thetemperature at the time of producing a polyester is prevented, an aspectof which is thus economically advantageous for the production of apolyester, and the matter that the diol is solidified depending upon thekind thereof is prevented. On the other hand, when the storagetemperature within the storage tank of the diol is not higher than 230°C., not only the matter that high-pressure storage equipment becomesnecessary is prevented by suppressing evaporation of the diol, an aspectof which is thus economically advantageous, but deterioration of thediol can be prevented.

In general, a pressure within the storage tank of the diol is preferablya slightly elevated pressure by dry nitrogen or dry air. In the casewhere the pressure is too low or too high, the control equipment becomescomplicated, an aspect of which is thus economically disadvantageous.

In the present invention, as to a content of the oxidation product ofthe diol which is used for the production of a polymer with a goodcolor, in general, an upper limit thereof is preferably not more than10,000 ppm, more preferably not more than 5,000 ppm, still morepreferably not more than 3,000 ppm, and most preferably not more than2,000 ppm. On the other hand, though a lower limit thereof is notparticularly limited, in general, it is preferably 1 ppm or more. Forthe reason of economy of the purification step, the lower limit is morepreferably 10 ppm or more, and more preferably 100 ppm or more.

In the present invention, the diol is in general purified by means ofdistillation.

As the biomass-resource-derived polyurethane according to the presentinvention, all of polyurethanes produced from polyester polyols whichare produced through a reaction of components composed mainly of variouscompounds falling within the scopes of the above-enumerated dicarboxylicacid units and diol units are included in the polyurethane of thepresent invention.

As a typical polyester polyol which is used for the production of thebiomass-resource-derived polyurethane according to the presentinvention, specifically, the following polyester polyols can beexemplified.

Examples of a polyester polyol using succinic acid include a polyesterpolyol composed of succinic acid and ethylene glycol, a polyester polyolcomposed of succinic acid and 1,3-propylene glycol, a polyester polyolcomposed of succinic acid and 2-methyl-1,3-propanediol, a polyesterpolyol composed of succinic acid and 3-methyl-1,5-pentanediol, apolyester polyol composed of succinic acid and neopentyl glycol, apolyester polyol composed of succinic acid and 1,6-hexamethylene glycol,a polyester polyol composed of succinic acid and 1,4-butanediol, apolyester polyol composed of succinic acid and1,4-cyclohexanedimethanol, and the like.

Examples of a polyester polyol using oxalic acid include a polyesterpolyol composed of oxalic acid and ethylene glycol, a polyester polyolcomposed of oxalic acid and 1,3-propylene glycol, a polyester polyolcomposed of oxalic acid and 2-methyl-1,3-propanediol, a polyester polyolcomposed of oxalic acid and 3-methyl-1,5-pentanediol, a polyester polyolcomposed of oxalic acid and neopentyl glycol, a polyester polyolcomposed of oxalic acid and 1,6-hexamethylene glycol, a polyester polyolcomposed of oxalic acid and 1,4-butanediol, a polyester polyol composedof oxalic acid and 1,4-cyclohexanedimethanol, and the like.

Examples of a polyester polyol using adipic acid include a polyesterpolyol composed of adipic acid and ethylene glycol, a polyester polyolcomposed of adipic acid and 1,3-propylene glycol, a polyester polyolcomposed of adipic acid and 2-methyl-1,3-propanediol, a polyester polyolcomposed of adipic acid and 3-methyl-1,5-pentanediol, a polyester polyolcomposed of adipic acid and neopentyl glycol, a polyester polyolcomposed of adipic acid and 1,6-hexamethylene glycol, a polyester polyolcomposed of adipic acid and 1,4-butanediol, a polyester polyol composedof adipic acid and 1,4-cyclohexanedimethanol, and the like.

In addition to the above, polyester polyols obtained using the foregoingdicarboxylic acid in combination are also preferable. Examples thereofinclude a polyester polyol composed of succinic acid, adipic acid, andethylene glycol, a polyester polyol composed of succinic acid, adipicacid, and 1,4-butanediol, a polyester polyol composed of terephthalicacid, adipic acid, and 1,4-butanediol, a polyester polyol composed ofterephthalic acid, succinic acid, and 1,4-butanediol, and the like.

In general, a molecular weight calculated from a hydroxyl value of sucha polyester polyol is preferably from 500 to 5,000, more preferably from700 to 4,000, and still more preferably from 800 to 3,000. When themolecular weight is 500 or more, when formed into a polyurethane resin,satisfactory physical properties are obtained. In addition, when themolecular weight is not more than 5,000, the viscosity of the polyesterpolyol does not become excessively high, and handling properties aregood.

Furthermore, in general, a molecular weight distribution of such apolyester polyol as measured by GPC (gel permeation chromatography) ispreferably from 1.2 to 4.0, more preferably from 1.5 to 3.5, and stillmore preferably from 1.8 to 3.0. When the molecular weight distributionis 1.2 or more, economy of the production is enhanced. In addition, whenit is not more than 4.0, physical properties of the polyurethane resinare enhanced.

In addition, these polyester polyols may be used solely, or may be usedin admixture of two or more kinds thereof. Furthermore, the polyesterpolymer may be used upon being mixed with a polyether polyol or apolycarbonate diol, or may be used upon being modified into a copolymerpolyol.

Furthermore, in the case where the polyurethane reaction is carried outin the absence of a solvent, such a polyester polyol is preferablyliquid at 40° C., and more preferably, a viscosity thereof at 40° C. isnot more than 15,000 mPa·s.

(3) Organic acid having a pKa value at 25° C. of not more than 3.7:

Examples of the organic acid having a pKa value at 25° C. of not morethan 3.7 include organic acids described in Kagaku-binran (ChemicalHandbook) (Basic Edition), pp. 1054 to 1059, Maruzen Publishing Co.,Ltd. (1966); and CRC Handbook of Chemistry and Physics, 75^(th) Edition,p. 8-43 to p. 8-56, CRC Press (1995).

Of these, a lower limit value of the pKa value is preferably 2.0 ormore, more preferably 2.5 or more, and especially preferably 3.1 ormore; and an upper limit value thereof is preferably not more than 3.5.Incidentally, among the organic acids, there are compounds displayingtwo or more pKa values. In the present invention, the pKa value of acompound as referred to in that case means the lowest value.

Though the organic acid having a pKa value at 25° C. of not more than3.7 is not particularly limited, organic acids having three or moreactive hydrogen groups per molecule are preferable; malic acid, citricacid, tartaric acid, and a mixture thereof are more preferable; malicacid and a mixture thereof are the most preferable; and malic acidespecially preferable.

In particular, in the case of using succinic acid as a raw material,there may be the case where malic acid is contained in the raw materialsuccinic acid depending upon the production method of succinic acid. Insuch case, the production of a polyester polyol can also be carried outby as a combination with a diol component choosing malic acid-containingsuccinic acid and using it as it is or using it by adding malic acidaccording to the need.

In the organic acid having three or more active hydrogen groups permolecule, its pKa value tends to decrease due to effect of OH group at aposition of carbonyl group as compared with that of an organic acidhaving not more than 2 active hydrogen groups per molecule.

For example, when the case of malic acid having a pKa value at 25° C. of3.4 is explained as an example, if the content of malic acid in thesuccinic acid is more than 1,000 ppm, a branched structure in thepolyester polyol increases. Therefore, gelation at the time of apolyurethane reaction and unexpected polymerization are liable to occur,so that not only the control of the reaction becomes difficult, but alinear polyurethane having excellent physical properties may not beobtained. In addition, conversely, if malic acid is not contained atall, the mechanical strength tends to decrease depending upon theapplication.

For the foregoing reasons, as to the content of the organic acid havinga pKa value at 25° C. of not more than 3.7, in general, a lower limitvalue thereof is more than 0 ppm, preferably 0.001 ppm or more, morepreferably 0.01 ppm or more, still more preferably 0.05 ppm or more,especially preferably 0.07 ppm or more, and most preferably 0.1 ppm ormore relative to the dicarboxylic acid. An upper limit thereof is ingeneral not more than 1,000 ppm, preferably not more than 800 ppm, andmore preferably not more than 600 ppm.

In the present description, an analysis (detection) method of theorganic acid having a pKa value at 25° C. of not more than 3.7 isclassified into two cases, and the analysis is carried out in accordancewith these cases.

In the case where the content of the organic acid is 100 ppm or more,the analysis is carried out by means of high performance liquidchromatography. Specifically, a column equivalent to ULTRON PS-80H, 8.0mm I.D.×30 cm, manufactured by Shinwa Chemical Industries Ltd. is used;a column temperature is kept at 60° C.; a 0.1% perchloric acid aqueoussolution is used as an eluent and allowed to pass at a flow rate of 1.0mL/min; and each of components is fractionated. For the detection, an RIdetector and a UV detector are used depending upon the sensitivity ofthe component to be analyzed.

In the case where the content of the organic acid is less than 100 ppm,the analysis is carried out by means of LC-MS. Specifically, a columnequivalent to MCI GEL CK08EH (8.0 mm×300 mm L.), manufactured byMitsubishi Chemical Corporation is used; a column temperature is kept at60° C.; a 0.02% formic acid aqueous solution is used as an eluent andallowed to pass at a flow rate of 1.0 mL/min; and fractionatedcomponents are successively introduced into an MS detector. Thefractionated component having been introduced into the MS detector isdetected by ESI-SIM (negative) as a pseudo-molecular ion signal of thecomponent which is an analysis object. As an organic acid peak, S/N=3was defined as a detection limit.

When the content of the organic acid in the dicarboxylic acid is morethan 1,000 ppm, the viscosity of the polyester polyol as a polyurethaneraw material becomes high; the handling operability is deteriorated; anda polyurethane having poor mechanical characteristics such asflexibility, elasticity, etc. with an abnormally high molecule weight,an abnormally large molecular weight distribution, due to gelation orthe like at the time of polyurethane reaction tends to be formed. Inaddition, when the content of the organic acid in the dicarboxylic acidis more than 1,000 ppm, a scatter of the content is liable to be caused,and not only physical properties of the resulting polyurethane arevariable, but even in the production step, the stable operation tends tobecome difficult.

When the content of the organic acid in the dicarboxylic acid is morethan 0 ppm, not only the matter that the purification step of thedicarboxylic acid becomes complicated is prevented, an aspect of whichis thus economically advantageous, and when formed into a polyurethane,the mechanical strength can be enhanced.

(4) Polyisocyanate Compound:

Examples of the polyisocyanate compound which is used in the presentinvention include aromatic diisocyanates such as 2,4- or 2,6-tolylenediisocyanate, xylylene diisocyanate, 4,4′-diphenylmethane diisocyanate(MDI), p-phenylene diisocyanate, 1,5-naphthalene diisocyanate, tolidinediisocyanate, etc.; aromatic ring-containing aliphatic diisocyanatessuch as α,α,α′,α′-tetramethylxylylene diisocyanate, etc.; aliphaticdiisocyanates such as methylene diisocyanate, propylene diisocyanate,lysine diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylenediisocyanate, 1,6-hexamethylene diisocyanate, etc.; alicyclicdiisocyanates such as 1,4-cyclohexane diisocyanate, methylcyclohexanediisocyanate (hydrogenated TDI),1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (IPDI),4,4′-dicyclohexylmethane diisocyanate,isopropylidenedicyclohexyl-4,4′-diisocyanate, etc.; and the like. Thesemay be used solely or in combination of two or more kinds thereof.

In the present invention, aromatic polyisocyanates having especiallyhigh reactivity are preferable, and in particular, tolylene diisocyanate(TDI) and diphenylmethane diisocyanate (hereinafter sometimes referredto as “MDI”) are preferable. In addition, polyisocyanates in which apart of NCO groups thereof is modified into urethane, urea, burette,allophanate, carbodiimide, oxazolidone, amide, imide, or the like may beused, and furthermore, polynuclear bodies include those containing anisomer other than the foregoing.

In general, a use amount of such a polyisocyanate compound is preferablyfrom 0.1 equivalents to 10 equivalents, more preferably from 0.8equivalents to 1.5 equivalents, and still more preferably from 0.9equivalents to 1.05 equivalents to 1 equivalent of the hydroxyl group ofthe polyester polyol, and the hydroxyl group and amino group of thechain extender.

When the use amount of the polyisocyanate is not more than 10equivalents, the matter that an unreacted isocyanate group causes anundesirable reaction is prevented, and desired physical properties areeasily obtainable. In addition, when the use amount of thepolyisocyanate is 0.1 equivalents or more, the molecular weights of thepolyurethane and the polyurethaneurea become sufficiently large, so thatdesired performances can be revealed.

In the present invention, a chain exchanger having two or more activehydrogens may be used according to the need. The chain extender isclassified mainly into a compound having two or more hydroxyl groups anda compound having two or more amino groups. Of these, a short-chainpolyol, specifically a compound having two or more hydroxyl groups, ispreferable for the polyurethane application; and a polyamide compound,specifically a compound having two or more amino groups, is preferablefor the polyurethane application.

In addition, in the polyurethane resin of the present invention, when acompound having a molecular weight (number average molecular weight) ofnot more than 500 is used in combination as the chain extender, rubberelasticity of a polyurethane elastomer is enhanced, and hence, such ismore preferable from the standpoint of physical properties.

Examples of the compound having two or more hydroxyl groups includealiphatic glycols such as ethylene glycol, diethylene glycol,triethylene glycol, propylene glycol, dipropylene glycol, tripropyleneglycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol,2,3-butanediol, 3-methyl-1,5-pentanediol, neopentyl glycol,2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol,2-butyl-2-ethyl-1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol,2-methyl-2,4-pentanediol, 2,2,4-trimethyl-1,3-pentanediol,2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol,2-butyl-2-hexyl-1,3-propanediol, 1,8-octanediol,2-methyl-1,8-octanediol, 1,9-nonanediol, etc.; alicyclic glycols such asbishydroxymethylcyclohexane, etc.; aromatic ring-containing glycols suchas xylylene glycol, bishydroxyethoxybenzene, etc.; and the like.

Examples of the compound having two or more amino groups includearomatic diamines such as 2,4- or 2,6-tolylenediamine, xylylenediamine,4,4′-diphenylmethanediamine, etc.; aliphatic diamines such asethylenediamine, 1,2-propylenediamine, 1,6-hexanediamine,2,2-dimethyl-1,3-propanediamine, 2-methyl-1,5-pentanediamine,1,3-diaminopentane, 2,2,4- or 2,4,4-trimethylhexanediamine,2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine,1,9-nonanediamine, 1,10-decanediamine, etc.; alicyclic diamines such as1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (IPDA),4,4′-dicyclohexylmethanediamine (hydrogenated MDA),isopropylidenecyclohexyl-4,4′-diamine, 1,4-diaminocyclohexane,1,3-bisaminomethylcyclohexane, etc.; and the like.

Of these, ethylene glycol, diethylene glycol, 1,3-propanediol,1,4-butanediol, 3-methyl-1,5-pentanediol, neopentyl glycol,2-methyl-1,3-propanediol, isophoronediamine, hexamethylenediamine,ethylenediamine, propylenediamine, 1,3-diaminopentane, and2-methyl-1,5-pentanediamine are preferable in the present invention.

In these chain extenders, when the aromatic polyisocyanate is used, onehaving a hydroxyl group is preferable, whereas when the aliphaticpolyisocyanate is used, one having an amino group is preferable. Inaddition, these chain extenders may be used solely or in combination oftwo or more kinds thereof. Though a use amount of such a chain extenderis not particularly limited, in general, it is preferably 0.1equivalents or more and not more than 10 equivalents to 1 equivalent ofthe polyester polyol.

When the use amount of the chain extender is not more than 10equivalents, the matter that the resulting polyurethane andpolyurethaneurea resins become excessively rigid is prevented, desiredcharacteristics are obtained, and the resins are easily soluble in asolvent, so that processing is easy. In addition, when the use amount ofthe chain extender is 0.1 equivalents or more, the resultingpolyurethane and polyurethane resins do not become excessively soft,sufficient strength and elasticity recovering performance or elasticityretaining performance are obtained, and high-temperature characteristicscan be enhanced.

In addition, for the purpose of controlling the molecular weight of thepolyurethane resin, a chain terminator having one active hydrogen groupcan be used according to the need. Examples of such a chain terminatorinclude aliphatic monools having a hydroxyl group, such as ethanol,propanol, butanol, hexanol, etc.; and aliphatic monoamines having anamino group, such as diethylamine, dibutylamine, monoethanolamine,diethanolamine, etc. These may be used solely or in combination of twoor more kinds thereof.

In addition, for the purpose of increasing the heat resistance orstrength of the polyurethane resin, a crosslinking agent having three ormore active hydrogen groups can be used according to the need.Trimethylolpropane, glycerin and isocyanate modified products thereof,polymeric MDI, and the like can be used as such a crosslinking agent.

(5) Other Additives:

Furthermore, other additives than those described above may be added tothe polyurethane resin of the present invention according to the need.Examples of such additives include antioxidants such as CYANOX 1790(manufactured by Cyanamid), IRGANOX 245 and IRGANOX 1010 (all of whichare manufactured by Ciba Specialty Chemicals), Sumilizer GA-80(manufactured by Sumitomo Chemical Co., Ltd.),2,6-dibutyl-4-methylphenol (BHT), etc., light stabilizer such as TINUVIN622LD and TINUVIN 765 (all of which are manufactured by Ciba SpecialtyChemicals), SANOL LS-2626 and LS-765 (all of which are manufactured bySankyo Co., Ltd.), etc., ultraviolet ray absorbers such as TINUVIN 328and TINUVIN 234 (all of which are manufactured by Ciba SpecialtyChemicals), etc., silicone compounds such asdimethylsiloxane/polyoxyalkylene copolymers, additives and reactiveflame retardants such as red phosphorus, organophosphorus compounds,phosphorus- and halogen-containing organic compounds, bromine- orchlorine-containing organic compounds, ammonium polyphosphate, aluminumhydroxide, antimony oxide, etc., colorants such as pigments, e.g.,titanium dioxide, dyes, carbon black, etc., hydrolysis inhibitors suchas carbodiimide compounds, etc., fillers such as short glass fibers,carbon fibers, alumina, talc, graphite, melamine, China clay, etc.,lubricants, oils, surfactants, other inorganic extenders, organicsolvents, and the like. In addition, a blowing agent such as water,alternative to CFCs, etc. may be added. In particular, the blowing agentis useful for polyurethane foams for shoe sole.

<Production Method of Biomass-Resource-Derived Polyester Polyol>

A production method of a biomass-resource-derived polyester polyolaccording to the present invention, which contains, as constituentunits, an aliphatic diol unit, a dicarboxylic acid unit, and an organicacid unit having a pKa value at 25° C. of not more than 3.7, is notparticularly limited so far as a polyester polyol can be produced suchthat the dicarboxylic acid contains at least one component derived frombiomass resources; and that the content of the organic acid unit is morethan 0% by mole and not more than 0.09% by mole relative to thedicarboxylic unit.

An example of the production method of a biomass-resource-derivedpolyester polyol according to the present invention is hereunderdescribed.

In particular, a dicarboxylic acid component derived from biomassresources may be mixed with a dicarboxylic acid component not derivedfrom biomass resources and used as the dicarboxylic acid. In the case ofusing the mixture, adipic acid, sebacic acid, and the like arepreferable from the standpoints of costs and performance.

In addition, it is preferable to use ethylene glycol, diethylene glycol,1,4-butanediol, and the like solely or in admixture as the diol unitfrom the standpoints of costs and performance, but it should not beconstrued that the present invention is limited thereto.

In the present invention, in using, as a polyester polyol formingreaction raw material, the dicarboxylic acid derived from biomassresources and/or diol obtained by the foregoing method, the polyesterpolyol may be produced within a reaction tank in which an oxygenconcentration during the polyester polyol production reaction iscontrolled to not more than a specified value.

According to this, coloration of the polyester polyol due to anoxidation reaction of the nitrogen compound that is an impurity, orcoloration of the polyester polyol due to a diol oxidation reaction of2-(4-hydroxybutyloxy)tetrahydrofuran or the like as formed by anoxidation reaction of 1,4-butanediol in the case of using, for example,1,4-butanediol as the diol, can be suppressed, and therefore, apolyester polyol with a good color can be produced.

The foregoing production reaction is defined as a reaction of from,after charging the raw materials in an esterification reaction tank, apoint of time of starting temperature rising to produce a polymer havinga desired viscosity in the reaction tank at ordinary pressure or underreduced pressure until subjecting the reaction tank to pressure recoveryfrom the reduced pressure to ordinary pressure or higher.

As to an oxygen concentration in the reaction tank during the productionreaction, though a lower limit thereof is not particularly limited, ingeneral, it is preferably 1.0×10⁻⁹% or more, and more preferably1.0×10⁻⁷% or more relative to a total volume of the reaction tank. Ingeneral, an upper limit thereof is preferably not more than 10%, morepreferably not more than 1%, still more preferably not more than 0.1%and most preferably not more than 0.01%. When the oxygen concentrationis 1.0×10⁻⁹% or more, the matter that the control step becomescomplicated can be prevented. In addition, when the oxygen concentrationis not more than 10%, the matter that coloration of the polyester polyolbecomes conspicuous can be prevented.

In the case of feeding the dicarboxylic acid derived from biomassresources into the reaction tank, so far as the dicarboxylic acid is asolid, it can be fed into the reaction tank as it stands in a state ofthe fed solid. It is important to carry out the operation before thestart of the esterification reaction such that the oxygen concentrationwithin the reaction tank is a desired concentration during the feedingor after the feeding. At the time of regulating the oxygenconcentration, there may be the case where the raw material dicarboxylicacid is blown up into a gas phase, thereby making the operationdifficult. Thus, it is desirable to adopt a particle size (averageparticle size) of the raw material dicarboxylic acid at the time offeeding of from 0.01 mm to 100 mm, and preferably from 0.05 mm to 10 mm.

In addition, in feeding the dicarboxylic acid derived from biomassresources as the polyester polyol raw material into the reaction tank,the dicarboxylic acid can be fed in a molten state, or a dissolving tankwith the raw material polyol or a suitable solvent is provided beforethe reaction tank, and the dicarboxylic acid can be fed as a rawmaterial solution or suspension into the reaction tank.

In addition, in using the dicarboxylic acid derived from biomassresources as a polyester polyol raw material, the oxygen concentrationand humidity at the time of taking a method of transferring thedicarboxylic acid from the storage tank into the reactor may becontrolled. According to this, corrosion within a transfer pipe to becaused due to a sulfur component that is an impurity can be prevented.Furthermore, coloration to be caused due to an oxidation reaction of anitrogen source can be suppressed, and a polyester polyol with a goodcolor can be produced.

Specifically, examples of the kind of the transfer pipe include knownmetal-made transfer pipes or those in which a lining of glass, a resin,or the like is applied to an inner surface thereof, glass-made orresin-made containers, and the like. From the standpoint of strength orthe like, metal-made transfer pipes or those in which a lining isapplied are preferable.

As a material of the metal-made tank, known materials are used.Specifically, examples thereof include carbon steels, ferrite basedstainless steels, martensite based stainless steels such as SUS410,etc., austenite based stainless steels such as SUS310, SUS304, SUS316,etc., clad steels, cast iron, copper, copper alloys, aluminum, Inconel,Hastelloy, titanium, and the like.

As to an oxygen concentration within the transfer pipe, though a lowerlimit thereof is not particularly limited, in general, it is preferably0.00001% or more, and more preferably 0.01% or more relative to thetotal volume of the transfer pipe. On the other hand, in general, alower limit thereof is preferably not more than 16%, more preferably notmore than 14%, and still more preferably not more than 12%. When theoxygen concentration is 0.00001% or more, the matter that the investmentin plant and equipment or the control step becomes complicated isprevented, an aspect of which is thus economically advantageous. On theother hand, when the oxygen concentration is not more than 16%,coloration of the produced polyester polyol can be suppressed.

As to a humidity within the transfer pipe, though a lower limit thereofis not particularly limited, in general, it is preferably 0.0001% ormore, more preferably 0.001% or more, still more preferably 0.01% ormore, and most preferably 0.1% or more; and an upper limit thereof ispreferably not more than 80%, more preferably not more than 60%, andstill more preferably not more than 40%.

When the humidity within the transfer pipe is 0.0001% or more, thematter that the control step becomes complicated is prevented, an aspectof which is thus economically advantageous. In addition, when thehumidity within the transfer pipe is not more than 80%, corrosion of thestorage tank or piping can be prevented. Furthermore, when the humiditywithin the transfer pipe is not more than 80%, problems such asattachment of the dicarboxylic acid onto the storage tank or piping,blocking of the dicarboxylic acid, etc. can be prevented, and corrosionof the piping to be caused due to such an attachment phenomenon can besuppressed.

As to a temperature within the transfer pipe, in general, a lower limitthereof is preferably −50° C. or higher, and more preferably 0° C. orhigher. On the other hand, in general, an upper limit thereof ispreferably not higher than 200° C., more preferably not higher than 100°C., and still more preferably not higher than 50° C. When thetemperature is −50° C. or higher, the storage costs can be suppressed.In addition, when the temperature is not higher than 200° C.,concurrence of a dehydration reaction of the carboxylic acid or the likecan be prevented.

In general, a pressure within the transfer pipe is preferably from 0.1kPa to 1 MPa, and from the viewpoint of operability, it is morepreferably 0.05 MPa or more and not more than 0.3 MPa.

A use amount of the diol which is used at the time of producing apolyester polyol is substantially equimolar to the diol amount necessaryfor obtaining a polyester polyol having a desired molecular weightrelative to the molar number of the dicarboxylic acid or a derivativethereof. In general, in view of the fact that distillation is revealedduring the ester condensation and/or ester exchange reaction, it ispreferable to use the diol in an excessive amount by from 0.1 to 20% bymole.

In addition, it is preferable to carry out the ester condensation and/orester exchange reaction in the presence of an esterification catalyst.An addition timing of the esterification catalyst is not particularlylimited, and the esterification catalyst may be added at the time ofcharging the raw materials, or it may be added after removing water tosome extent or at the time of starting the pressure reduction.

In the case where the dicarboxylic acid is used as a raw material, theraw material dicarboxylic acid displays autocatalysis, and therefore, itis general that the reaction is allowed to proceed at the beginning ofthe reaction without adding a catalyst, and, when the rate becomesinsufficient in conformity with a formation rate of formed water, anesterification catalyst which is different from the raw materialcomponent is added. At that time, as to a timing of adding theesterification catalyst which is different from the raw materialcomponent, when a progressing esterification reaction rate is preferablynot more than ⅓, and more preferably not more than ⅕ as compared withthe esterification reaction rate at the beginning of the reactionwithout adding a catalyst, the reaction is easily controllable, andhence, such is preferable.

Examples of the esterification catalyst include compounds containing ametal element belonging to the Group 1 to the Group 14 of the periodictable exclusive of hydrogen and carbon. Specifically, examples thereofinclude organic group-containing compounds such as carboxylates, alkoxysalts, organic sulfonates, β-diketonate salts, etc., each containing atleast one metal selected from the group consisting of titanium,zirconium, tin, antimony, cerium, germanium, zinc, cobalt, manganese,iron, aluminum, magnesium, calcium, strontium, sodium, and potassium;inorganic compounds such as oxides or halides of the foregoing metals,etc.; and mixtures thereof.

There may be the case where the foregoing catalyst component iscontained in the polyester polyol raw material derived from biomassresources from the reasons described above. In that case, such a rawmaterial may be used as it is as a metal-containing raw material withoutparticularly purifying the raw material.

Of these, metal compounds containing titanium, zirconium, germanium,zinc, aluminum, magnesium, or calcium, and mixtures thereof arepreferable. Above of all, titanium compounds, zirconium compounds, andgermanium compounds are especially preferable. In addition, for thereason that when the catalyst is in a molten or dissolved state at thetime of an esterification condensation reaction, the reaction rateincreases, the catalyst is preferably a compound which is in a liquidform at the time of an esterification reaction or soluble in a desiredpolyester polyol.

As the titanium compounds, for example, tetraalkyl titanates arepreferable. Specifically, examples thereof include tetra-n-propyltitanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyltitanate, tetraphenyl titanate, tetracyclohexyl titanate, tetrabenzyltitanate, and mixtures thereof.

In addition, examples of the preferred titanium compound includetitanium (oxy)acetylacetonate, titanium tetraacetylacetonate, titanium(diisopropoxide)acetylacetonate, titanium bis(ammoniumlactato)dihydroxide, titanium bis(ethyl acetoacetato)diisopropoxide,titanium (triethanolaminato)isopropoxide, polyhydroxytitanium stearate,titanium lactate, titanium triethanolaminate, butyl titanate dimer, andthe like.

Moreover, examples of the preferred titanium compound also includetitanium oxide and a composite oxide containing titanium and silicon(for example, a titania/silica composite oxide). Of these,tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyltitanate, titanium (oxy)acetylacetonate, titanium tetraacetylacetonate,titanium bis(ammonium lactato)dihydroxide, polyhydroxytitanium stearate,titanium lactate, butyl titanate dimer, titanium oxide, and atitania/silica composite oxide are preferable; tetra-n-butyl titanate,titanium (oxy)acetylacetonate, titanium tetraacetylacetonate,polyhydroxytitanium stearate, titanium lactate, butyl titanate dimer,and a titania/silica composite oxide are more preferable; andtetra-n-butyl titanate, polyhydroxytitanium stearate,titanium(oxy)acetylacetonate, titanium tetraacetylacetonate, and atitania/silica composite oxide are especially preferable.

Specifically, examples of the zirconium compound include zirconiumtetraacetate, zirconium acetate hydroxide, zirconiumtris(butoxy)stearate, zirconyl diacetate, zirconium oxalate, zirconyloxalate, potassium zirconium oxalate, polyhydroxyzirconium stearate,zirconium ethoxide, zirconium tetra-n-propoxide, zirconiumtetraisopropoxide, zirconium tetra-n-butoxide, zirconiumtetra-t-butoxide, zirconium tributoxyacetylacetonate, and mixturesthereof.

Furthermore, for example, zirconium oxide, or for example, a compositeoxide containing zirconium and silicon is also preferably used as thezirconium compound. Of these, zirconyl diacetate, zirconiumtris(butoxy)stearate, zirconium tetraacetate, zirconium acetatehydroxide, ammonium zirconium oxalate, potassium zirconium oxalate,polyhydroxyzirconium stearate, zirconium tetra-n-propoxide, zirconiumtetraisopropoxide, zirconium tetra-n-butoxide, and zirconiumtetra-t-butoxide are preferable; zirconyl diacetate, zirconiumtetraacetate, zirconium acetate hydroxide, zirconiumtris(butoxy)stearate, ammonium zirconium oxalate, zirconiumtetra-n-propoxide, and zirconium tetra-n-butoxide are more preferable;and zirconium tris(butoxy)stearate are especially preferable.

Specifically, examples of the germanium compound include inorganicgermanium compounds such as germanium oxide, germanium chloride, etc.;and organic germanium compounds such as a tetraalkoxygermanium, etc.From the standpoints of costs and easiness of availability, germaniumoxide, tetraethoxygermanium, tetrabutoxygermanium, and the like arepreferable, with germanium oxide being especially preferable.

As to a use amount of the catalyst in the case of using a metal compoundas such an esterification catalyst, in general, a lower limit valuethereof is preferably 1 ppm or more, and more preferably 3 ppm or more,and in general, an upper limit value thereof is not more than 30,000ppm, more preferably not more than 1,000 ppm, still more preferably notmore than 250 ppm, and especially preferably not more than 130 ppm, interms of a metal amount relative to the formed polyester polyol. Whatthe amount of the used catalyst is not more than 30,000 ppm is not onlyeconomically advantageous but enables the polyester polyol to haveenhanced thermal stability. In addition, what the amount of the usedcatalyst is 1 ppm or more enables the polyester polyol to have enhancedpolymerization activity.

As to a reaction temperature of the esterification condensation reactionand/or ester exchange reaction between the dicarboxylic acid componentand the diol component, in general, a lower limit thereof is preferably150° C. or higher, and more preferably 180° C. or higher, and ingeneral, an upper limit thereof is preferably not higher than 260° C.,and more preferably not higher than 250° C. A reaction atmosphere is ingeneral an inert gas atmosphere of nitrogen, argon, or the like. Ingeneral, a reaction pressure is preferably from ordinary pressure to 10Torr, and more preferably from ordinary pressure to 100 Torr.

As to a reaction time, in general, a lower limit thereof is preferably10 minutes or longer, and in general, an upper limit thereof ispreferably not longer than 10 hours, and more preferably not longer than5 hours.

In addition, the esterification reaction is carried out at ordinarypressure or under reduced pressure, the timing of pressure reduction andthe degree of pressure reduction are adopted chiefly in conformity witha reaction rate and a boiling point of the raw material diol, or in thecase of making an azeotropic solvent coexistent, in conformity with aboiling point thereof. In order to carry out a preferred stableoperation, it is preferable that the reaction is carried out at ordinarypressure at the time of starting an esterification reaction, and after aprogressing esterification reaction rate reaches not more than ½ of theinitial rate, the pressure reduction is started at a preferred timing.The pressure reduction may be started either before or after thecatalyst adding timing.

In the present invention, as a reaction apparatus for producing apolyester, known vertical or horizontal stirring tank reactors can beused. For example, there is exemplified a method of using a stirringtank type reactor equipped with an exhaust pipe for pressure reductionconnecting a vacuum pump and a reactor to each other. In addition, amethod in which a condenser is coupled with the exhaust pipe forpressure reduction connecting a vacuum pump and a reactor to each other,and volatile components formed during the polycondensation reaction andunreacted raw materials are recovered by the condenser is preferable.

In an industrial production method, the reaction is decided chiefly byan outflow of the distillation component, thereby determining an endpoint of the reaction, and an appropriate outflow depends upon a boilingpoint (easiness of flowing out) of the raw material polyol component. Ingeneral, the reaction end point is determined by an acid number duringthe reaction. In addition, as the case may be, a treatment of regulatingthe polyester polyol so as to have a desired molecular weight(recondensation or depolymerization by the addition of the raw materialdiol) is added. Th reaction control is determined on the basis of theacid number. In addition, in general, the reaction end point is decidedin conformity with the outflow. However, after completion of thereaction, an acid number of such a product is measured, and when theacid number falls outside the target standard, the esterificationreaction is again carried out, thereby regulating it so as to have adesired acid number.

The acid number which is defined as the reaction end is preferably notmore than 1.0, more preferably not more than 0.5, and still morepreferably not more than 0.2. In addition, a preferred water content atthe time of completion of the reaction is preferably not more than 200ppm, more preferably not more than 100 ppm, and still more preferablynot more than 50 ppm. In order to regulate appropriate acid number andwater content at the time of end point, as the case may be, the reactioncan also be carried out by adding an azeotropic solvent capable ofcausing azeotropy with water and forming two phases and not havingactive hydrogen. Though this azeotropic solvent is not particularlylimited so far as it has such performances, it is generally aninexpensive aromatic compound such as benzene, toluene, etc.

In addition, after the polyester polyol production reaction, thepolyester polyol can be stored as it is or fed for the polyurethanereaction, or after carrying out a treatment of deactivating the addedcatalyst, the polyester polyol can be stored or fed for the polyurethanereaction. Though a method of deactivating the added catalyst is notparticularly limited, it is preferable to use a catalyst deactivatingadditive such as phosphite trimester, etc., and a method involving aconcern that the polyester polyol structure is broken, such as a watertreatment, etc., is rather unsuitable.

<Biomass-Resource-Derived Polyester Polyol>

The biomass-resource-derived polyester polyol according to the presentinvention is a polyester polyol containing, as constituent units, atleast an aliphatic diol unit, a dicarboxylic acid unit, and an organicacid unit having a pKa value at 25° C. of not more than 3.7, wherein thedicarboxylic acid contains at least one component derived from biomassresources, and the content of the organic acid unit is more than 0% bymole and not more than 0.09% by mole relative to the dicarboxylic acidunit.

Though a lower limit of the content of the organic acid unit is notparticularly limited, it is preferably 9×10⁻⁸% by mole or more, morepreferably 9×10⁻⁷% by mole or more, still more preferably 4.5×10⁻⁶% bymole or more, especially preferably 6.3×10^(0.6)% by mole or more, andmost preferably 9×10⁻⁶% by mole or more; and an upper limit thereof ispreferably not more than 9×10⁻²% by mole, more preferably not more than7.2×10⁻²% by mole, and still more preferably not more than 5.4×10⁻²% bymole, relative to the dicarboxylic acid unit.

When the content of the organic acid unit is more than 0.09% by mole,the viscosity of the polyester polyol as a polyurethane raw materialbecomes high; the handling operability is deteriorated; and apolyurethane having an abnormally high molecule weight, an abnormallylarge molecular weight distribution, or poor mechanical characteristicssuch as flexibility, elasticity, etc. due to gelation or the like at thetime of polyurethane reaction tends to be formed. In addition, when thecontent of the organic acid unit is more than 0.09% by mole, a scatterof the content is liable to be caused, and not only physical propertiesof the resulting polyurethane are variable, but even in the productionstep, the stable operation tends to become difficult.

In addition, when the content of the organic acid unit is more than 0%by mole, not only the matter that the purification step of thedicarboxylic acid becomes complicated is prevented, an aspect of whichis thus economically advantageous, but when formed into a polyurethane,the mechanical strength can be enhanced.

Though the polyester polyol of the present invention is not particularlylimited on whether it is a solid or a liquid (in a liquid state) atordinary temperature, it is preferably a liquid at ordinary temperaturefrom the standpoint of handling.

In general, a molecular weight calculated from hydroxyl number of such apolyester polyol is preferably from 500 to 5,000, more preferably from700 to 4,000, and still more preferably from 800 to 3,000. When themolecular weight is 500 or more, when formed into a polyurethane resin,satisfactory physical properties are obtainable. In addition, when themolecular weight is not more than 5,000, the viscosity of the polyesterpolyol does not become excessively high, and handling properties areenhanced.

Furthermore, in general, a molecular weight distribution of such apolyester polyol as measured by GPC (gel permeation chromatography) ispreferably from 1.2 to 4.0, more preferably from 1.5 to 3.5, and stillmore preferably from 1.8 to 3.0. When the molecular weight distributionis 1.2 or more, the economy of the production is enhanced, whereas whenit is not more than 4.0, physical properties of the polyurethane resincan be enhanced.

It is preferable that a content of nitrogen atoms contained in thepolyester polyol of the present invention other than those contained incovalently bonded functional groups is not more than 1,000 ppm relativeto the mass of the polyester polyol. The content of nitrogen atomscontained in the polyester polyol of the present invention other thanthose contained in covalently bonded functional groups is preferably notmore than 500 ppm, more preferably not more than 100 ppm, and still morepreferably not more than 50 ppm. Above all, it is preferably not morethan 40 ppm, more preferably not more than 30 ppm, and most preferablynot more than 20 ppm.

The content of nitrogen atoms contained in the polyester polyol of thepresent invention other than those contained in covalently bondedfunctional groups is mainly derived from nitrogen atoms in the rawmaterial. When the content of nitrogen atoms contained in the polyesterpolyol of the present invention other than those contained in covalentlybonded functional groups is not more than 20 ppm, coloration becomessmall.

In general, the polyester polyol produced in the present invention ispreferably a polyester polyol with less coloration. As to a value of thepolyester polyol of the present invention as expressed by a Hazen colornumber (APHA value: in conformity with JIS-K0101), an upper limitthereof is preferably not more than 50, more preferably not more than40, still more preferably not more than 30, and especially preferablynot more than 25. On the hand, though a lower limit thereof is notparticularly limited, in general, it is preferably 1 or more, morepreferably 2 or more, and still more preferably 5 or more.

As to a polyester polyol having an APHA value of not more than 50, forexample, there is brought such an advantage that the use application offilms, sheets, and the like of a polyurethane using the polyester polyolas a raw material is not restricted. On the other hand, as to apolyester polyol having an APHA value of 1 or more, a production processof producing a polyester polyol is not complicated, does not requireextremely expensive investment in plant and equipment, and iseconomically advantageous.

<Production Method of Biomass-Resource-Derived Polyurethane>

The production method of a biomass-resource-derived polyurethane in thepresent invention is a method for producing a polyurethane including atleast a step of reacting an aliphatic diol and a dicarboxylic acid toproduce a polyester polyol; and a step of reacting the polyester polyoland a polyisocyanate compound, wherein the dicarboxylic acid that is araw material contains at least one component derived from biomassresources, and a content of an organic acid having a pKa value at 25° C.of not more than 3.7 in the dicarboxylic acid is more than 0 ppm and notmore than 1,000 ppm. There are no particular limitations so far as atleast the biomass-resource-derived polyurethane can be produced suchthat the dicarboxylic acid to be used as a raw material falls within theforegoing range.

In the production method of a biomass-resource-derived polyurethaneaccording to the present invention, it is necessary to use raw materialsunder specified conditions. Furthermore, by combining various productionconditions in processes until producing a polyurethane, abiomass-resource-derived polyurethane containing, as constituent units,at least an aliphatic diol unit, a dicarboxylic acid unit, apolyisocyanate unit, and an organic acid unit having a pKa value at 25°C. of not more than 3.7, wherein the dicarboxylic acid contains at leastone component derived from biomass resources, and a content of theorganic acid unit is more than 0% by mole and not more than 0.09% bymole relative to the dicarboxylic acid unit, can be first produced.

An example of the production method of a biomass-resource-derivedpolyurethane according to the present invention is hereunder described.

The polyurethane of the present invention may be produced through areaction in a bulk state, namely in the absence of a solvent, or througha reaction in a solvent having excellent solubility against thepolyurethane, such as aprotic polar solvents.

An example of the production method in the copresence of an aproticsolvent is hereunder described, but the production method is notparticularly limited so far as it is carried out in the copresence of anaprotic solvent. Examples of the production method include one-stagemethod and two-stage method.

The one-stage method as referred to herein is a method of reacting abiomass-resource-derived polyester polyol, a polyisocyanate compound,and a chain extender together.

In addition, the two-stage method as referred to herein is a method offirst reacting a biomass-resource-derived polyester polyol and apolyisocyanate compound to prepare a prepolymer, both ends of which areterminated with an isocyanate group, and then reacting the prepolymerwith a chain extender (hereinafter also referred to as “isocyanategroup-terminated two-stage method”). In addition, examples of thetwo-stage method include a method in which after preparing a prepolymer,both ends of which are terminated with a hydroxyl group, the prepolymerand a polyisocyanate are reacted.

Above all, the isocyanate group-terminated two-stage method goes througha step of reacting a polyester polyol with 1 equivalent or more of apolyisocyanate in advance, thereby preparing an intermediate, both endsof which are terminated with an isocyanate, corresponding to a softsegment of the polyurethane.

The two-stage method has such a characteristic feature that when theprepolymer is once prepared and then reacted with the chain extender,the molecular weight of the soft segment portion is easily regulated,distinct phase separation between the soft segment and the hard segmentis easily achieved, and performances as an elastomer are easilyrevealed.

In particular, in the case where the chain extender is a diamine, thischain extender considerably differs in the reaction rate with theisocyanate group from the hydroxyl group of the polyester polyol.Therefore, it is more preferable to carry out polyurethaneurea formationby the prepolymer method.

[One-Stage Method]

The one-stage method as referred to herein is also called a one-shotmethod and is a method in which the biomass-resource-derived polyesterpolyol, the polyisocyanate compound, and the chain extender are chargedtogether and reacted. The use amounts of the respective compounds may bethe same as those described above.

In the one-shot method, a solvent may be used, or may not be used. Inthe case where a solvent is not used, the polyisocyanate component andthe polyol component may be stirred and mixed using a low-pressurefoaming machine or a high-pressure foaming machine, or using ahigh-speed rotary mixer.

In the case of using a solvent, examples of the solvent include ketonessuch as acetone, methyl ethyl ketone, methyl isobutyl ketone,cyclohexanone, etc.; ethers such as dioxane, tetrahydrofuran, etc.;hydrocarbons such as hexane, cyclohexane, etc.; aromatic hydrocarbonssuch as toluene, xylene, etc.; esters such as ethyl acetate, butylacetate, etc.; halogenated hydrocarbons such as chlorobenzene,trichlene, perchlene, etc.; aprotic polar solvents such asγ-butyrolactone, dimethyl sulfoxide, N-methyl-2-pyrrolidone,N,N-dimethylformamide, N,N-dimethylacetamide, etc.; and mixtures of twoor more kinds thereof.

In the present invention, of these organic solvents, in the case ofproducing a polyurethane, aprotic polar solvents are preferable from theviewpoint of solubility, an aspect of which is a characteristic featureof the present invention. Furthermore, specific examples of thepreferred aprotic polar solvent are exemplified. That is, methyl ethylketone, methyl isobutyl ketone, N,N-dimethylacetamide,N,N-dimethylformamide, N-methyl-2-pyrrolidone, and dimethyl sulfoxideare more preferable, with N,N-dimethylformamide andN,N-dimethylacetamide being especially preferable.

In the case of the one-shot method (reaction in one stage), as to anNCO/active hydrogen group (polyester polyol and chain extender) reactionequivalent ratio, in general, a lower limit thereof is preferably 0.50,and more preferably 0.8; and in general, an upper limit thereof ispreferably 1.5, and more preferably 1.2.

When the reaction equivalent ratio is not more than 1.5, the matter thatthe excessive isocyanate groups cause side reactions to giveunpreferable influences to physical properties of the polyurethane canbe prevented. In addition, where the reaction equivalent ratio is 0.50or more, the molecular weight of the resulting polyurethane sufficientlyincreases, and the generation of problems on strength or thermalstability can be prevented.

In general, the respective components are preferably reacted at from 0to 100° C. It is preferable that this temperature is regulated by theamount of the solvent, reactivity of the raw materials used, reactionequipment, and the like. Too low temperatures are undesirable becausethe reaction proceeds too slowly, and the raw materials andpolymerization product have low solubility, resulting in poorproductivity. In addition, too high temperatures are undesirable becauseside reactions and decomposition of the polyurethane resin occur. Thereaction may be carried out under reduced pressure while degassing.

In addition, a catalyst, a stabilizer, or the like may be added for thereaction according to the need.

Examples of the catalyst include triethylamine, tributylamine,dibutyltin dilaurate, stannous octylate, acetic acid, phosphoric acid,sulfuric acid, hydrochloric acid, sulfonic acids, and the like.

Examples of the stabilizer include 2,6-dibutyl-4-methylphenol, distearylthiodipropionate, di-β-naphthylphenylenediamine, tri(dinonylphenyl)phosphite, and the like.

[Two-Stage Method]

The two-stage method is also called a prepolymer process. In thismethod, in general, the polyisocyanate component and the polyolingredient are reacted in a reaction equivalent ratio of preferably from1.0 to 10.00 in advance, thereby producing a prepolymer. Subsequently, apolyisocyanate component and an active hydrogen compound component suchas a polyhydric alcohol, an amine compound, etc. are added to theprepolymer, thereby carrying out a two-stage reaction. In particular, amethod in which the polyol component is reacted with a polyisocyanatecompound in an amount of at least one equivalent to the polyolingredient to form a prepolymer, both ends of which are terminated withNCO, and a short-chain diol or a diamine that is a chain extender isthen allowed to act on the prepolymer to obtain a polyurethane, isuseful.

In the two-stage method, a solvent may be used, or may not be used. Inthe case of using a solvent, examples of the solvent include ketonessuch as acetone, methyl ethyl ketone, methyl isobutyl ketone,cyclohexanone, etc.; ethers such as dioxane, tetrahydrofuran, etc.;hydrocarbons such as hexane, cyclohexane, etc.; aromatic hydrocarbonssuch as toluene, xylene, etc.; esters such as ethyl acetate, butylacetate, etc.; halogenated hydrocarbons such as chlorobenzene,trichlene, perchlene, etc.; aprotic polar solvents such asγ-butyrolactone, dimethyl sulfoxide, N-methyl-2-pyrrolidone,N,N-dimethylformamide, N,N-dimethylacetamide, etc.; and mixtures of twoor more kinds thereof.

In the present invention, of these organic solvents, in the case ofproducing a polyurethane, aprotic polar solvents are preferable from theviewpoint of solubility, an aspect of which is a characteristic featureof the present invention. Furthermore, specific examples of thepreferred aprotic polar solvent are exemplified. That is,N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone,and dimethyl sulfoxide are more preferable, with N,N-dimethylformamideand N,N-dimethylacetamide being especially preferable.

In synthesizing a prepolymer terminated with an isocyanate group, any ofthe following methods may be used: (1) a polyisocyanate compound isfirst reacted directly with the polyester polyol without using asolvent, to synthesize a prepolymer, and this prepolymer is used as itis; (2) a prepolymer is synthesized by the method (1) and then dissolvedin a solvent, followed by providing for the use; and (3) a solvent isused from the beginning to react a polyisocyanate and a glycol.

In the case of the method (1), it is important in the present inventionthat a polyurethane is obtained in the state of coexisting with asolvent by a method in which in allowing a chain extender to act, thechain extender is dissolved in a solvent, or the prepolymer and thechain extender are simultaneously introduced into a solvent, or thelike.

As to an NCO/active hydrogen group (polyester polyol) reactionequivalent ratio, in general, a lower limit thereof is preferably 1, andmore preferably 1.1; and in general, an upper limit thereof ispreferably 10, more preferably 5, and still more preferably 3.

A use amount of the chain extender is not particularly limited. Ingeneral, a lower limit thereof is preferably 0.8, and more preferably 1,and in general, an upper limit thereof is preferably 2, and morepreferably 1.2, relative to the equivalent of the NCO group contained inthe prepolymer.

When the foregoing ratio is not more than 2, the matter that theexcessive isocyanate groups cause side reactions to give unpreferableinfluences to physical properties of the polyurethane can be prevented.In addition, where the foregoing ratio is 0.8 or more, the molecularweight of the resulting polyurethane sufficiently increases, and thegeneration of problems on strength or thermal stability can beprevented.

In addition, a monofunctional organic amine or alcohol may be allowed tocoexist at the time of reaction.

In general, the respective components are reacted preferably at from 0to 250° C. It is preferable that this temperature is regulated by theamount of the solvent, reactivity of the raw materials used, reactionequipment, and the like. Too low temperatures are undesirable becausethe reaction proceeds too slowly, and the raw materials andpolymerization product have low solubility, resulting in poorproductivity. In addition, too high temperatures are undesirable becauseside reactions and decomposition of the polyurethane resin occur. Thereaction may be carried out under reduced pressure while degassing.

In addition, a catalyst, a stabilizer, or the like may be added for thereaction according to the need.

Examples of the catalyst include triethylamine, tributylamine,dibutyltin dilaurate, stannous octylate, acetic acid, phosphoric acid,sulfuric acid, hydrochloric acid, sulfonic acids, and the like. However,in the case where the chain extender is one having high reactivity suchas short-chain aliphatic amines, etc., it is preferable that thereaction is carried out without adding a catalyst.

Examples of the stabilizer include 2,6-dibutyl-4-methylphenol, distearylthiodipropionate, di-β-naphthylphenylenediamine, tri(dinonylphenyl)phosphite, and the like.

When a generally used petroleum-derived dicarboxylic acid is used at thetime of polyurethane production, the reaction is hardly controlled atthe time of urethane reaction, the molecular weight becomes abnormallyhigh due to gelation or the like, or the molecular weight distributionbecomes abnormally large. However, when the foregoing dicarboxylic acidin which the amount of the organic acid to be contained falls within aspecified range is used, astonishingly, it is possible to control thereaction at the time of urethane reaction, and the foregoing problems donot occur. In consequence, since a linear biomass-resource-derivedpolyurethane can be produced, handling properties of the polyurethaneare enhanced. In addition, by regulating a formulation depending upon anapplication thereof, the polyurethane can be used in a wide field.

At the time of polyurethane production of the present invention, in thecase of adding a crosslinking agent for an application requiring heatresistance or strength, it is preferable to make its addition amountlarger than that at the time of using a generally used petroleum-deriveddicarboxylic acid. In addition, since the viscosity of the polyurethaneobtained at the time of polyurethane production of the present inventionis low, at the time of post-treatment and processing of thepolyurethane, it is preferable to make the temperature slightly lowerthan that at the time of using petroleum-derived succinic acid,resulting in favorable handling properties, stability and economy.

<Artificial Leather/Synthetic Leather>

An artificial leather or synthetic leather of the present invention isdescribed in detail. The artificial leather or synthetic leather iscomposed of, as major constituent elements, a base cloth, an adhesivelayer, and a skin layer. The skin layer is a skin layer blended liquidobtained by mixing the polyurethane resin obtained in the presentinvention with other resins, an antioxidant, an ultraviolet rayabsorber, etc. to fabricate a polyurethane resin solution, which is thenmixed with a coloring agent, an organic solvent, etc. To thepolyurethane resin solution, in addition to the above, a hydrolysisinhibitor, a pigment, a dye, a flame retardant, a filler, a crosslinkingagent, etc. can be added according to the need.

Examples of other resins include polyurethane resins other than that ofthe present invention, poly(meth)acrylate resins, vinyl chloride-vinylacetate based copolymers, vinyl chloride-vinyl propionate basedcopolymers, polyvinyl butyral based resins, cellulose based resins,polyester resins, epoxy resins, phenoxy resins, polyamide resins, andthe like.

Examples of the crosslinking agent include polyisocyanate compounds suchas organic polyisocyanates, crude MDI, a TDI adduct oftrimethylolpropane, triphenylmethane isocyanate, etc. and the like.

Examples of the base cloth include Tetoron/rayon, a napped cotton cloth,a knitted cloth, a nylon tricot cloth, and the like. In addition,examples of the adhesive include two-pack polyurethane resins composedof a polyurethane resin, a polyisocyanate compound, and a catalyst.

In addition, examples of the polyisocyanate compound include a TDIadduct of trimethylolpropane and the like. Examples of the catalystinclude amine based or tin based catalysts.

Next, the production method of a synthetic leather according to thepresent invention is described. That is, the above-obtained polyurethaneresin is mixed with other resin, etc. to fabricate a polyurethane resinsolution, which is then mixed with a coloring agent, etc. to fabricate askin layer blended liquid. Subsequently, this blended liquid is coatedon a release paper and dried; an adhesive is further coated to form anadhesive layer; a napped cloth or the like is laminated thereon anddried; and after aging at room temperature for a few days, the releasepaper is released, thereby obtaining the synthetic leather of thepresent invention.

The artificial leather/synthetic leather of the present invention can beused for clothing, shoe, bag, and the like.

The polyurethane for shoe sole according to the present invention isdescribed in detail. Examples of the production method of a polyurethanefoam for shoe sole using the foregoing polyester polyol include mainly(1) a method in which at the time of reacting a polyisocyanate componentand a polyol component and expanding the reaction product to produce apolyurethane foam, as the polyol component, the foregoing polyesterpolyol-containing polyol component is used (hereinafter referred to as“Production Method A”); and (2) a method in which at the time ofreacting an isocyanate prepolymer obtained by reacting a polyisocyanatecomponent and a polyol component with a polyol component and expandingthe reaction product to produce a polyurethane foam, the foregoingpolyester polyol-containing polyol component is used as the polyolcomponent which is used as a raw material of the isocyanate prepolymer(hereinafter referred to as “Production Method B”).

First of all, Production Method A is described. In Production Method A,as the polyol component which is used at the time of reacting apolyisocyanate component and a polyol component and expanding thereaction product to produce a polyurethane foam, the foregoing polyesterpolyol-containing polyol component is used.

The polyol component can contain, in addition to the foregoing polyesterpolyol, other polyester polyol, a polyether polyol such as polypropyleneglycol, polyoxytetramethylene glycol, etc., polycaprolactone polyol,polycarbonate polyol, and the like. These may be used solely, or may beused in admixture of two or more kinds thereof.

Representative examples of the polyisocyanate component which is usedfor Production Method A include an isocyanate prepolymer and the like.The isocyanate prepolymer is obtained by stirring and reacting apolyisocyanate monomer and a polyol in the presence of an excessivepolyisocyanate monomer in the usual way.

Specific examples of the polyisocyanate monomer include polyisocyanatecompounds such as tolylene diisocyanate, m-phenylene diisocyanate,p-phenylene diisocyanate, xylylene diisocyanate, diphenylmethanediisocyanate, hexamethylene diisocyanate, isophorone diisocyanate,polymethylene polyphenyl diisocyanate, dimethyl-4,4-biphenylenediisocyanate, etc.; and modified products thereof, for example,carbodiimide modified products, etc.

These may be used solely, or may be used in admixture of two or morekinds thereof. Of these, a single use of 4,4-diphenylmethanediisocyanate or a joint use of 4,4-diphenylmethane diisocyanate with acarbodiimide modified product thereof is preferable.

As to an NCO % of the isocyanate prepolymer, from the viewpoint ofpreventing the matter that a viscosity thereof is high so that moldingby a low-pressure foaming machine becomes difficult, the NCO % ispreferably 15% or more, and more preferably 17% or more; and from theviewpoint of preventing the matter that the viscosity is low so thatweighing accuracy of the foaming machine becomes low, the NCO % ispreferably not more than 25%, more preferably not more than 23%, andstill more preferably not more than 22%.

The isocyanate prepolymer assumes a liquid at a temperature of 15° C. orhigher and can be discharged even at a low temperature, and therefore, apolyurethane foam can be easily produced even at a molding temperatureof, for example, from 40 to 50° C.

In Production Method A, at the time of reacting the polyisocyanatecomponent and the polyol component, it is preferable to regulate aproportion between the both such that an isocyanate index is from 95 to110.

In Production Method A, a polyurethane foam can be produced by mixingand stirring the polyisocyanate component and the polyol component by amolding machine, injecting the mixture into a molding die, and expandingit. More specifically, a polyurethane foam can be produced by regulatinga temperature of the polyol component to a temperature of usually about40° C. by using, for example, a tank, etc. and then mixing and reactingthe polyol component and the polyisocyanate component using a foamingmachine such as an automatic mixing and injection type foaming machine,an automatic mixing and injection type foaming machine, etc.

In addition, according to Production Method A, a urethane shoe sole canbe molded by mixing the polyisocyanate component and the polyolcomponent and then molding the mixture by a foaming machinetemperature-controlled to usually from about 40 to 50° C.

Next, Production Method B is described. In Production Method B, at thetime of reacting an isocyanate prepolymer obtained by reacting apolyisocyanate component and a polyol component with a polyol componentand expanding the reaction product to produce a polyurethane foam, asthe polyol component which is used at the time of preparing anisocyanate prepolymer, the foregoing polyester polyol-containing polyolcomponent is used.

As the polyester polyol contained in the polyol component which is usedat the time of preparing an isocyanate prepolymer, the polyester polyolof the present invention is used. Examples of the polyisocyanatecomponent that is a production raw material of the isocyanate prepolymerinclude the polyisocyanate monomer which is used in Production Method A,and the like.

Examples of the polyisocyanate monomer include the same materials as thespecific examples of the polyisocyanate monomer used in ProductionMethod A. Incidentally, of these exemplified materials, a single use of4,4-diphenylmethane diisocyanate or a joint use of 4,4-diphenylmethanediisocyanate with a carbodiimide modified product thereof is preferable.

In Production Method B, by using the foregoing polyester polyol, theviscosity of the resulting isocyanate prepolymer can be suitably kept,so that a polyurethane foam having excellent mechanical strength can beobtained.

The polyol component can contain, in addition to the foregoing polyesterpolyol, other polyester polyol. Examples of the other polyester polyolcomponent include the same materials as those used in Production MethodA.

A content of the foregoing polyester polyol in the polyol component ispreferably from 10 to 100% by weight, and more preferably from 50 to100% by weight. A content of the other polyester polyol is preferablyfrom 0 to 90% by weight, and more preferably from 0 to 50% by weight.

In addition, in general, it is preferable to regulate a proportionbetween the polyisocyanate component and the polyol component such thatan NCO group/OH group equivalent ratio is preferably from about 5 to 30.

Subsequently, an isocyanate prepolymer is obtained by mixing, stirringand reacting the polyisocyanate component and the polyol component andoptionally, an additive in the usual way.

As to an NCO % of the thus obtained isocyanate prepolymer, from theviewpoint of reducing the viscosity to make it easy to achieve moldingby a low-pressure foaming machine, the NCO % is preferably 12% or more,and more preferably 14% or more; and from the viewpoint of imparting anappropriate viscosity to enhance weighing accuracy of the foamingmachine, the NCO % is preferably not more than 25%, more preferably notmore than 23%, and still more preferably not more than 22%.

The isocyanate prepolymer assumes a liquid at a temperature of 15° C. orhigher and can be discharged even at a low temperature, and therefore, apolyurethane foam can be favorably produced even at a moldingtemperature of, for example, from 40 to 50° C.

Subsequently, a polyurethane foam is obtained by reacting and expandingthe isocyanate prepolymer and the polyol component.

Examples of the polyol component which is used for the reaction with theisocyanate prepolymer include the same materials as other polyols thanthe polyester polyol which is used as the polyol component in ProductionMethod A.

Incidentally, to the polyol component which is used for the reactionwith the isocyanate prepolymer, a chain extender, a blowing agent, apolyurethane catalyst, a stabilizer, pigment, or the like may beproperly added in an appropriate amount, according to the need.

In Production Method B, at the time of reacting the polyisocyanatecomponent and the polyol component, it is preferable to regulate aproportion between the both such that an isocyanate index is from 95 to110.

In addition, in Production Method B, a polyurethane foam can be producedby mixing and stirring the isocyanate prepolymer and the polyolcomponent and optionally, an additive by a molding machine, injectingthe mixture into a molding die, and expanding it. More specifically, apolyurethane foam can be produced by regulating a temperature of thepolyol component to a temperature of usually about 40° C. by using, forexample, a tank, etc. and then mixing and reacting it with theisocyanate prepolymer using a foaming machine such as an automaticmixing and injection type foaming machine, an automatic mixing andinjection type foaming machine, etc.

In addition, according to Production Method B, a urethane shoe sole canbe molded by mixing the isocyanate prepolymer and the polyol componentand then molding the mixture by a foaming machine temperature-controlledto usually from about 40 to 50° C. In the case of adopting ProductionMethod B for producing a shoe sole, as to the resulting polyurethanefoam, nevertheless an amount of the resin peer unit volume decreases,mechanical strength such as tensile strength, tear strength, etc. can besufficiently enhanced.

Thus, from the viewpoints of revealing sufficient mechanical strengthand contriving to realize low density, a density of a molded article ofthe polyurethane foam obtained by Production Method A or ProductionMethod B is preferably from 0.15 to 1.0 g/cm³, and more preferably from0.2 to 0.4 g/cm³.

<Physical Properties of Biomass-Resource-Derived Polyurethane>

The biomass-resource-derived polyurethane according to the presentinvention is a polyurethane containing, as constituent units, at leastan aliphatic diol unit, a dicarboxylic acid unit, and an organic acidunit having a pKa value at 25° C. of not more than 3.7, wherein thedicarboxylic acid contains at least one component derived from biomassresources, and the content of the organic acid unit is more than 0% bymole and not more than 0.09% by mole relative to the dicarboxylic acidunit.

Though a lower limit of the content of the organic acid unit is notparticularly limited, it is preferably 9×10⁻⁸% by mole or more, morepreferably 9×10⁻⁷% by mole or more, still more preferably 4.5×10⁻⁶% bymole or more, especially preferably 6.3×10⁻⁶% by mole or more, and mostpreferably 9×10⁻⁶% by mole or more; and an upper limit thereof ispreferably not more than 9×10⁻²% by mole, more preferably not more than7.2×10^(0.2)% by mole, and still more preferably not more than 5.4×10⁻²%by mole, relative to the dicarboxylic acid unit.

When the content of the organic acid unit is more than 0.09% by mole, apolyurethane having an abnormally high molecule weight, an abnormallylarge molecular weight distribution, or poor mechanical characteristicssuch as flexibility, elasticity, etc. due to gelation or the like at thetime of polyurethane reaction tends to be formed. In addition, when thecontent of the organic acid unit is more than 0.09% by mole, a scatterof the content is liable to be caused, and not only physical propertiesof the resulting polyurethane are variable, but even in the productionstep, the stable operation tends to become difficult. On the other hand,when the content of the organic acid unit is more than 0% by mole, apolyurethane having high mechanical strength tends to be formed.

In addition, it is preferable that the biomass-resource-derivedpolyurethane according to the present invention has the followingphysical properties.

When the physical properties of the polyurethane of the presentinvention are described by reference to a polyurethane between analiphatic diol and an aliphatic dicarboxylic acid, such as polybutylenesuccinate or polybutylene succinate adipate, it is preferable that thepolyurethane has very broad physical property characteristics such as atensile stress of from 5 to 15 MPa and an elongation at break of from300 to 1,500%.

In addition, in the case where a specified application is subjective, apolyurethane having arbitrary broad range characteristics exceeding theforegoing range region can be formed. These characteristics can bearbitrarily regulated by varying the kind of the polyurethane rawmaterial or additive, the polymerization condition, the moldingcondition, and the like depending upon the use purpose.

Ranges of representative physical property values which the polyurethaneof the present invention has are hereunder disclosed in detail.

As to a composition ratio of the polyurethane copolymer, it ispreferable that a molar ratio of the diol unit and the dicarboxylic acidunit is substantially equal.

As to a content of the sulfur atom in the polyurethane of the presentinvention, an upper limit thereof is preferably not more than 50 ppm,more preferably not more than 5 ppm, still more preferably not more than3 ppm, and most preferably not more than 0.3 ppm as reduced into an atomrelative to the mass of the polyurethane. On the other hand, though alower limit thereof is not particularly limited, it is preferably 0.0001ppm or more, more preferably 0.001 ppm or more, still more preferably0.01 ppm or more, especially preferably 0.05 ppm or more, and mostpreferably 0.1 ppm or more.

When the content of the sulfur atom is not more than 50 ppm, the thermalstability or hydrolysis resistance of the polyurethane can be enhanced.In addition, when the content of the sulfur atom is 0.001 ppm or more,the matter that the purification costs become conspicuously high isprevented, an aspect of which is thus economically advantageous in theproduction of a polyurethane.

In the polymer of the present invention, in particular, in the case of apolyurethane using a raw material derived from biomass resources, thereis a tendency that a volatile organic component, for example,tetrahydrofuran, acetaldehyde, etc. is liable to be contained in thepolyurethane. As to a content of the volatile organic component, ingeneral, an upper limit thereof is preferably not more than 10,000 ppm,more preferably not more than 3,000 ppm, still more preferably not morethan 1,000 ppm, and most preferably not more than 500 ppm in thepolyurethane. On the other hand, though a lower limit thereof is notparticularly limited, in general, it is preferably 1 ppb or more, morepreferably 10 ppb or more, and still more preferably 100 ppb or more.

When the amount of the volatile material is not more than 10,000 ppm,the matter that the volatile component causes an odor is prevented, anddeterioration of the expansion or storage stability at the time of meltmolding can be prevented. On the other hand, when the amount of thevolatile material is 1 ppb or more, not only extremely expensiveinvestment in plant and equipment is not required for the purpose ofproducing a polymer, but a long production time is not required, anaspect of which is thus economically advantageous.

In general, the polyurethane which is produced in the present inventionis preferably a polyurethane with less coloration. As to a YI value (inconformity with JIS-K7105) of the polyurethane of the present invention,an upper limit thereof is preferably not more than 20, more preferablynot more than 10, still more preferably not more than 5, and especiallypreferably not more than 3. On the other hand, though a lower limitthereof is not particularly limited, in general, it is preferably −20 ormore, more preferably −5 or more, and still more preferably −1 or more.

A polyurethane having a YI value of not more than 20 has such anadvantage that the use application of films, sheets, and the like is notrestricted. On the other hand, as to a polyurethane having a YI value of−20 or more, a production process of producing a polymer is notcomplicated, does not require extremely expensive investment in plantand equipment, and is economically advantageous.

A weight average molecular weight of the polyurethane by means of GPCmeasurement varies depending upon an application, and in general, it ispreferably from 10,000 to 1,000,000, more preferably from 50,000 to500,000, still more preferably from 100,000 to 400,000, and especiallypreferably from 100,000 to 300,000 in terms of a polyurethanepolymerization solution. A molecular weight distribution is preferablyfrom 1.5 to 3.5, more preferably from 1.8 to 2.5, and still morepreferably from 1.9 to 2.3 in terms of Mw/Mn.

When the foregoing molecular weight is not more than 1,000,000, thematter that the viscosity of the solution becomes excessively high isprevented, and handling properties are enhanced. In addition, when themolecular weight is 10,000 or more, the matter that the physicalproperties of the resulting polyurethane are excessively lowered can beprevented. When the molecular weight distribution is 1.5 or more, thematter that the economy of the polyurethane production is excessivelydeteriorated is prevented, and an elastic modulus of the resultingpolyurethane is enhanced. In addition, when the molecular weightdistribution is not more than 3.5, the matter that the viscosity of thesolution becomes excessively high is prevented, and handling propertiesare enhanced. In addition, the matter that an elastic modulus of theresulting polyurethane becomes excessively high is prevented, andelastic recovery is enhanced.

As polyurethane molded articles, for example, synthetic leather orartificial leather, polyurethane for shoe sole, films, sheets, tubes,moisture permeable resins, and the like, in general, a weight averagemolecular weight of the polyurethane is preferably from 10,000 to1,000,000, more preferably from 50,000 to 500,000, still more preferablyfrom 100,000 to 400,000, and especially preferably from 150,000 to350,000. A molecular weight distribution is preferably from 1.5 to 3.5,more preferably from 1.8 to 2.5, and still more preferably from 1.9 to2.3 in terms of Mw/Mn.

When the foregoing molecular weight is not more than 1,000,000, thematter that the viscosity of the solution becomes excessively high isprevented, and handling properties become good. In addition, when themolecular weight is 10,000 or more, the matter that the physicalproperties of the resulting polyurethane are excessively lowered can beprevented. When the molecular weight distribution is 1.5 or more, theeconomy of the polyurethane production becomes good, and an elasticmodulus of the resulting polyurethane can be enhanced. In addition, whenthe molecular weight distribution is not more than 3.5, the matter thatthe viscosity of the solution becomes excessively high is prevented, andhandling properties become good. In addition, the matter that an elasticmodulus of the resulting polyurethane becomes excessively high isprevented, and elastic recovery can be enhanced.

A solution containing the polyurethane produced in the present invention(hereinafter also referred to as “polyurethane solution”) is convenientfor processing into films, yarns, etc. because gelation hardly proceeds;the smaller the change in viscosity with a lapse of time, the better thestorage stability is; and thixotropy is small.

In general, a content of the polyurethane is preferably from 1 to 99% byweight, more preferably from 5 to 90% by weight, still more preferablyfrom 10 to 70% by weight, and especially preferably from 15 to 50% byweight relative to a total weight of the polyurethane solution having apolyurethane dissolved in an aprotic solvent. When the content of thepolyurethane is 1% by weight or more, the removal of a large amount ofthe solvent is not necessary, and the productivity can be enhanced. Inaddition, when the content of the polyurethane is not more than 99% byweight, the viscosity of the solution is suppressed, and the operabilityor processability can be enhanced.

Though the polyurethane solution is not particularly specified, in thecase of storing over a long period of time, it is preferable to store itin an inert gas atmosphere of nitrogen, argon, or the like.

<Polyurethane Molded Article/Application>

The polyurethane and urethane prepolymer solution thereof as produced bythe present invention can reveal a variety of characteristics and can bewidely used as foams, elastomers, coating materials, fibers, adhesives,flooring materials, sealants, medical materials, artificial leathers,and the like.

The polyurethane, polyurethaneurea, and urethane prepolymer solutionthereof as produced by the present invention are also usable as acasting polyurethane elastomer. Examples thereof include rolls such asrolling rolls, papermaking rolls, business appliances, pretensioningrolls, etc.; solid tires, casters, or the like for fork lift trucks,automotive vehicle newtrams, carriages, carriers, and the like; andindustrial products such as conveyor belt idlers, guide rolls, pulleys,steel pipe linings, rubber screens for ore, gears, connection rings,liners, impellers for pumps, cyclone cones, cyclone liners, etc. Inaddition, the polyurethane, polyurethaneurea, and urethane prepolymersolution thereof are applicable to belts for OA apparatus, paper feedrolls, squeegees, cleaning blades for copying, snowplows, toothed belts,surf rollers, and the like.

The polyurethane and urethane prepolymer solution thereof as produced bythe present invention are also applicable to an application asthermoplastic elastomers. For example, the polyurethane and the urethaneprepolymer solution can be used as tubes or hoses in pneumatic apparatusfor use in the food and medical fields, coating apparatus, analyticalinstruments, physicochemical apparatus, constant delivery pumps, watertreatment apparatus, industrial robots, and the like and as spiraltubes, hoses for firefighting, etc. In addition, the polyurethane andthe urethane prepolymer solution are usable as belts such as roundbelts, V-belts, flat belts, etc. in various transmission mechanisms,spinning machines, packaging apparatus, printing machines, and the like.

In addition, examples of elastomer applications include heel tops offootwear, shoe soles, apparatus parts such as cup rings, packings, balljoints, bushings, gears, rolls, etc., sports goods, leisure goods, beltsof wristwatches, and the like.

Furthermore, examples of automotive parts include oil stoppers, gearboxes, spacers, chassis parts, interior trims, tire chain substitutes,and the like. In addition, examples thereof include films such as keyboard films, automotive films, etc., curl cords, cable sheaths, bellows,conveying belts, flexible containers, binders, synthetic leathers,dipping products, adhesives, and the like.

The polyurethane and urethane prepolymer solution thereof as produced bythe present invention are also applicable to an application as a solventbased two-pack type coating material and can be applied to wood productssuch as musical instruments, family Buddhist altars, furniture,decorative plywood, sports goods, etc. In addition, the polyurethane andurethane prepolymer solution are also usable as a tar-epoxy-urethane forautomotive vehicle repair.

The polyurethane and urethane prepolymer solution thereof as produced bythe present invention are usable as a component of moisture-curableone-pack type coating materials, block isocyanate type solvent coatingmaterials, alkyd resin coating materials, urethane-modified syntheticresin coating materials, ultraviolet ray-curable coating materials, andthe like.

Such coating materials can be used, for example, as coating materialsfor plastic bumpers, strippable paints, coating materials for magnetictapes, overprint varnishes for floor tiles, flooring materials, paper,woodgrained films, and the like, varnishes for wood, coil coatings forhigh processing, optical fiber protection coatings, solder resists,topcoats for metal printing, base coats for vapor deposition, whitecoats for food cans, and the like.

The polyurethane and urethane prepolymer solution thereof as produced bythe present invention are applicable as an adhesive to shoes, footwear,magnetic tape binders, decorative papers, wood, structural members, andthe like. In addition, the polyurethane and urethane prepolymer solutioncan be used also as a component of adhesives for low-temperature use andhot-melt adhesives.

The polyurethane and urethane prepolymer solution thereof as produced bythe present invention are usable as a binder in applications such asmagnetic recording media, inks, castings, burned bricks, graftingmaterials, microcapsules, granular fertilizers, granular agriculturalchemicals, polymer cement mortars, resin mortars, rubber chip binders,reclaimed foams, glass fiber sizing, and the like.

The polyurethane and urethane prepolymer solution thereof as produced bythe present invention are usable as a component of fiber processingagents for shrink proofing, crease proofing, water repellent finishing,and the like.

The polyurethane, polyurethaneurea, and urethane prepolymer solutionthereof as produced by the present invention are applicable as asealant/caulking material to walls formed by concrete placing, inducedjoints, the periphery of sashes, wall type PC joints, ALC joints, andjoints of boards and as a sealant for composite glasses, sealant forheat-insulating sashes, sealant for automotive vehicles, and the like.

The polyurethane produced by the present invention is suitable forapplications to polyurethanes for shoe sole, synthetic leathers, andartificial leathers. In addition, at the time of using the polyurethaneproduced by the present invention, the polyester polyol component mayhave a skeleton of adipic acid, sebacic acid, or the like. Furthermore,since such a polyurethane of the present invention is derived fromplants and is biodegradable, it is further suitable for non-durableconsumer goods such as resins for shoe.

EXAMPLES

The present invention is hereunder described in more detail on the basisof the following Examples, but it should not be construed that thepresent invention is limited to the following Examples so far as thegist thereof is not deviated. Next, the present invention is describedin more detail by reference to the Examples.

(Measuring Method of Molecular Weight of Polyester Polyol)

A number average molecular weight of a polyester polyol was determinedin terms of a hydroxyl number (OH number, mg-KOH/g).

(Measuring Method of Molecular Weight of Polyurethane)

As to the measurement of a molecular weight of the resultingpolyurethane, a GPC apparatus, manufactured by Shimadzu Corporation(column: TSKgel Super HZM-N, solvent: lithium bromide-addedN,N-dimethylacetamide) was used, and a weight average molecular weightas reduced into standard polystyrene was defined as the molecularweight.

(Measuring Method of Physical Properties of Film)

A polyurethane resin test piece was fabricated in a strip form having awidth of 10 mm, a length of 100 mm, and a thickness of from 50 to 100 μMand measured using a tensile tester (Tensilon RTC-1210A, manufactured byOrietec Co., Ltd.). The measurement was carried out under a condition ofa chuck-to-chuck distance of 20 mm, a tensile rate of 200 mm/min, and atemperature of 23° C. (relative humidity: 55%). The measurement wascarried out at ten points per sample, and as to a stress at break and anelongation at break, average values thereof were adopted, respectively.

(APHA Value)

The APHA value was measured by the method in conformity with JIS-K0101.

(Content of Nitrogen Atom)

Several 10 mg of a sample was collected on a quartz boat, the sample wasburnt using a total nitrogen analyzer (TN-10 Model, manufacturedMitsubishi Chemical Corporation), and the content of a nitrogen atom wasdetermined by the chemical luminescence method.

(Content of Sulfur Atom)

About 0.1 g of a sample was collected on a platinum boat and burnt in aquartz tubular furnace (AQF-100 (concentration system), manufactured byMitsubishi Chemical Corporation), and a sulfur content in the combustiongas was absorbed by a 0.1% hydrogen peroxide aqueous solution.Thereafter, a sulfate ion in the absorbed solution was measured using anion chromatography (ICS-1000 Model, manufactured by Dionex Corporation).

An amount of a terminal carboxyl group is a value obtained by dissolvingthe resulting polyester in benzyl alcohol and titrated with 0.1 N NaOH,and it is a carboxyl equivalent per 1×10⁶ g.

(YI Value)

The YI value was measured by the method on the basis of JIS-K7105.

(Average Absorbance at from 250 to 300 nm)

The average absorbance was measured using a Hitachi's spectrophotometerUV-3500 and determined according to the method defined in the section of“MODES FOR CARRYING OUT THE INVENTION” of the present description.

(Analysis of Organic Acid and Sugar: High-Performance LiquidChromatography)

Column: ULTRON PS-80H, 8.0 mm I.D.×30 cm, manufactured by ShinwaChemical Industries Ltd.

Temperature: 60° C.

Eluent: 0.1% perchloric acid aqueous solution, 1.0 mL/min

Injection amount: 10 μL

Detection: RI detector or UV detector

A detection limit of malic acid was 100 ppm.

[Analysis of Malic Acid as a Minor Component (in the Case of Less than100 ppm): LC-MS]

Column: MCI GEL CK08EH (8.0 mm×300 mm L.), manufactured by MitsubishiChemical Corporation

Temperature: 60° C.

Eluent: 0.02% formic acid aqueous solution, 1.0 mL/min

Injection amount: 3 μL

Detection: ESI-SIM (negative), m/z 133.2 (malic acid pseudo-molecularion signal)

A detection limit of malic acid was 0.05 ppm at S/N of 3.

(Analysis of Amino Acid)

Apparatus: Hitachi's amino acid analyzer, L-8900

Analysis condition: Biological amino acid separation condition—ninhydrincolorimeter method (at 570 nm and 440 nm)

Standard product: PF (Wako's amino acid mixed liquid, ANII type 0.8 mL+Btype 0.8 mL→10 mL)

Injection amount: 10 μL

(Hydrolysis and Analysis for the Determination of the Amount of Protein)

A material obtained by precisely weighing 10 mg or 100 mg of a sampleand fixing its volume at 1 mL by pure water was dispensed 200 μL, dried,and heated in a hydrochloric acid atmosphere at 150° C. for one hour,thereby protein was hydrolyzed. This was dried and then again dissolvedupon adding 200 μL of pure water. The solution was filtered by a 0.45-μmfilter, and the filtrate was subjected to analysis of an amino acid. Anincrement of a total amino acid amount before and after the hydrolysiswas considered to be amount of protein.

The present invention is described in more detail by reference to thefollowing Examples, but it should not be construed that the presentinvention is limited to these Examples.

Referential Example 1

<Fabrication of Succinic Acid Fermenting Strain>

(A) Extraction of Brevibacterium flavum MJ233 Strain Genome DNA:

Brevibacterium flavum MJ233 was deposited as an accession number FERMP-3068, on Apr. 28, 1975, with the National Institute of Bioscience andHuman-Technology, Agency of Industrial Science and Technology, Ministryof International Trade and Industry (present Patent MicroorganismDepositary Center, National Institute of Advanced Industrial Science andTechnology) (Center 6, 1-1, Higashi 1-chome, Tsukuba-shi, Ibaraki-ken,305-8566 Japan) and converted to an international deposit under BudapestTreaty on May 1, 1981 with the accession number FERM BP-1497.

A Brevibacterium flavum MJ233 strain was cultured until a latelogarithmic growth phase on 10 mL of a medium A (obtained by dissolving2 g of urea, 7 g of (NH₄)₂SO₄, 0.5 g of KH₂PO₄, 0.5 g of K₂HPO₄, 0.5 gof MgSO₄.7H₂O, 6 mg of FeSO₄.7H₂O, 6 mg of MnSO₄.4-5H₂O, 200 μg ofbiotin, 200 μg of thiamine, 1 g of yeast extract, 1 g of casamino aid,and 20 g of glucose in 1 L of distilled water), and bacterial cells weregathered by means of centrifugation (10,000 G for 5 minutes).

The resulting bacterial cells were suspended in 0.15 mL of a solutioncontaining a 10 mM NaCl/20 mM tris buffer (pH 8.0)/1 mM EDTA.2Nasolution containing lysozyme so as to have a concentration of 10 mg/mL.Subsequently, Proteinase K was added to the foregoing suspension so asto have a final concentration of 100 μg/mL, and the mixture was kept at37° C. for one hour. Sodium dodecyl sulfate was further added so as tohave a final concentration of 0.5%, and the mixture was kept at 50° C.for 6 hours to cause bacteriolysis.

After the addition of an equal amount of a phenol/chloroform solution tothe resulting lysate solution and mild shaking at room temperature for10 minutes, the whole amount of the mixture was centrifuged (5,000 G for20 minutes at from 10 to 12° C.). The supernatant fraction wascollected, to which was then added sodium acetate in a concentration of0.3 M. To the resulting mixture was added two times the amount ofethanol, followed by mixing. The precipitate recovered by centrifugation(15,000 G for 2 minutes) was washed with 70% ethanol and then air-dried.To the resulting DNA, 5 mL of a 10 mM tris buffer (pH 7.5)/1 mM EDTA.2Nasolution was added. The mixture was allowed to stand overnight at 4° C.and then used as a template DNA for the subsequent PCR.

(B) Construction of Plasmid for PC Gene Promoter Substitution:

A DNA fragment of an N-terminated region of a pyruvate carboxylase geneoriginated from the Brevibacterium flavum MJ233 strain was obtained byPCR using the DNA prepared in the above (A) as a template and syntheticDNAs (SEQ ID NO: 1 and SEQ ID NO: 2) designed based on the sequence(Cg10689 of GenBank Database Accession No. BA000036) of the subject geneof a Corynebacterium glutamicum ATCC 13032 strain whose entire genomicsequence had been reported. Incidentally, as the DNA of SEQ ID NO: 1,one which was phosphorylated on the 5′-end thereof was used.

Composition of reaction liquid: 1 μL of the template DNA, 0.2 μL ofPfxDNA polymerase (manufactured by Invitrogen), 1-fold concentration ofan attached buffer, 0.3 μM of each primer, 1 mM of MgSO₄ and 0.25 μM ofdNTPS were mixed to give a total volume of 20 μL.

Reaction temperature condition: DNA Thermal Cycler PTC-200 (manufacturedby MJ Research) was used, and a cycle composed of 94° C. for 20 seconds,60° C. for 20 seconds and 72° C. for one minute was repeated 35 times.However, heat retention at 94° C. at the first cycle was conducted for 1minute and 20 seconds, while heat retention at 72° C. at the final cyclewas conducted for 4 minutes.

Confirmation of the amplified product was performed by separation by0.75% agarose (SeaKem GTG agarose, manufactured by FMC BioProducts) gelelectrophoresis and subsequent visualization with ethidium bromidestaining, whereby about 0.9 kb of a fragment was detected. The desiredDNA fragment was recovered from the gel using QIAquick Gel ExtractionKit (manufactured by QIAGEN). This was used as a PC gene N-terminatedfragment.

On the other hand, a TZ4 promoter fragment originated from theBrevibacterium flavum MJ233 strain, which is constitutionally highlyexpressed, was prepared by PCR using plasmid pMJPC1 (seeJP-A-2005-95169) as a template and synthetic DNAs described in SEQ IDNO: 3 and SEQ ID NO: 4. Incidentally, as the DNA of SEQ ID NO: 4, onewhich was phosphorylated on the 5′-end thereof was used.

Composition of reaction liquid: 1 μL of the template DNA, 0.2 μL ofPfxDNA polymerase (manufactured by Invitrogen), 1-fold concentration ofan attached buffer, 0.3 μM of each primer, 1 mM of MgSO₄ and 0.25 μM ofdNTPS were mixed to give a total volume of 20 L.

Reaction temperature condition: DNA Thermal Cycler PTC-200 (manufacturedby MJ Research) was used, and a cycle composed of 94° C. for 20 seconds,60° C. for 20 seconds and 72° C. for 30 seconds was repeated 25 times.However, heat retention at 94° C. at the first cycle was conducted for 1minute and 20 seconds, while heat retention at 72° C. at the final cyclewas conducted for 3 minutes.

Confirmation of the amplified product was performed by separation by1.0% agarose (SeaKem GTG agarose, manufactured by FMC BioProducts) gelelectrophoresis and subsequent visualization with ethidium bromidestaining, whereby about 0.5 kb of a fragment was detected. The desiredDNA fragment was recovered from the gel using QIAquick Gel ExtractionKit (manufactured by QIAGEN). This was used as a TZ4 promoter fragment.

The thus prepared PC gene N-terminated fragment and TZ4 promoterfragment were mixed and ligated using Ligation Kit ver. 2 (manufacturedby Takara Shuzo Co., Ltd.); thereafter, the ligated fragment was cleavedwith a restriction enzyme PstI and separated by 1.0% agarose (SeaKem GTGagarose, manufactured by FMC BioProducts) gel electrophoresis; and about1.0 kb of a DNA fragment was recovered using QIAquick Gel Extraction Kit(manufactured by QIAGEN). This was used as a TZ4 promoter/PC geneN-terminated fragment.

Furthermore, this DNA fragment was mixed with a DNA prepared by cleavingEscherichia coli plasmid pHSG299 (manufactured by Takara Shuzo Co.,Ltd.) with PstI and ligated using Ligation Kit ver. 2 (manufactured byTakara Shuzo Co., Ltd.). The resulting plasmid DNA was transformed withEscherichia coli (DH5α strain). The thus obtained recombinantEscherichia coli was smeared onto an LB agar medium containing 50 μg/mLof kanamycin and 50 μg/mL of X-Gal. Clones which had formed a whitecolony on the medium were subjected to liquid culture in the usual way,and the plasmid DNA was then purified. The resulting plasmid DNA wascleaved with a restriction enzyme PstI, whereby about 1.0 kb of aninserted fragment was recognized and named pMJPC17.1.

A DNA fragment of a 5′-upstream region of a pyruvate carboxylase geneoriginated from the Brevibacterium flavum MJ233 strain was obtained byPCR using the DNA prepared in Example 1-(A) as a template and syntheticDNAs (SEQ ID NO: 5 and SEQ ID NO: 6) designed based on the sequence(GenBank Database Accession No. BA000036) of the subject gene of aCorynebacterium glutamicum ATCC 13032 strain whose entire genomicsequence had been reported.

Composition of reaction liquid: 1 μL of the template DNA, 0.2 μL ofPfxDNA polymerase (manufactured by Invitrogen), 1-fold concentration ofan attached buffer, 0.3 μM of each primer, 1 mM of MgSO₄ and 0.25 μM ofdNTPS were mixed to give a total volume of 20 μL.

Reaction temperature condition: DNA Thermal Cycler PTC-200 (manufacturedby MJ Research) was used, and a cycle composed of 94° C. for 20 seconds,60° C. for 20 seconds and 72° C. for 30 seconds was repeated 35 times.However, heat retention at 94° C. at the first cycle was conducted for 1minute and 20 seconds, while heat retention at 72° C. at the final cyclewas conducted for 5 minutes.

Confirmation of the amplified product was performed by separation by1.0% agarose (SeaKem GTG agarose, manufactured by FMC BioProducts) gelelectrophoresis and subsequent visualization with ethidium bromidestaining, whereby about 0.7 kb of a fragment was detected. The desiredDNA fragment was recovered from the gel using QIAquick Gel ExtractionKit (manufactured by QIAGEN).

After phosphorylation on the 5′-end of the recovered DNA fragment withT4 Polynucleotide Kinase (manufactured by Takara Shuzo Co., Ltd.), theresulting fragment was bound to an SmaI site of an Escherichia colivector (manufactured by Takara Shuzo Co., Ltd.) by using Ligation Kitver. 2 (manufactured by Takara Shuzo Co., Ltd.), followed bytransformation of Escherichia coli (DH5α strain) with the resultingplasmid DNA. The thus obtained recombinant Escherichia coli was smearedonto an LB agar medium containing 50 μg/mL of ampicillin and 50 μg/mL ofX-Gal. Clones which had formed a white colony on the medium weresubjected to liquid culture in the usual way, and the plasmid DNA wasthen purified. The resulting plasmid DNA was provided for a PCR reactionwith, as primers, DNAs expressed by SEQ ID NO: 7 and SEQ ID NO: 6.

Composition of reaction liquid: 1 ng of the foregoing plasmid, 0.2 μL ofEx-TaqDNA polymerase (manufactured by Takara Shuzo Co., Ltd.), 1-foldconcentration of an attached buffer, 0.2 μM of each primer and 0.25 μMof dNTPS were mixed to give a total volume of 20 μL.

Reaction temperature condition: DNA Thermal Cycler PTC-200 (manufacturedby MJ Research) was used, and a cycle composed of 94° C. for 20 seconds,60° C. for 20 seconds and 72° C. for 50 seconds was repeated 20 times.However, heat retention at 94° C. at the first cycle was conducted for 1minute and 20 seconds, while heat retention at 72° C. at the final cyclewas conducted for 5 minutes.

In this way, the presence or absence of the thus inserted DNA fragmentwas recognized. As a result, the plasmid in which about 0.7 kb of theamplified product was recognized was selected and named pMJPC5.1.

Subsequently, the foregoing pMJPC17.1 and pMJPC5.1 were each cleavedwith a restriction enzyme XbaI and mixed, followed by ligation usingLigation Kit ver. 2 (manufactured by Takara Shuzo Co., Ltd.). This wascleaved with a restriction enzyme SacI and an restriction enzyme SphI,and the resulting DNA fragment was separated by 0.75% agarose (SeaKemGTG agarose, manufactured by FMC BioProducts) gel electrophoresis, andabout 1.75 kb of the DNA fragment was recovered using QIAquick GelExtraction Kit (manufactured by QIAGEN).

A DNA fragment obtained by inserting the TZ4 promoter between the5′-upstream region and the N-terminated region of this PC gene was mixedwith DNA prepared by cleaving an sacB gene-containing plasmid pKMB1 (seeJP-A-2005-95169) with SacI and SphI, followed by ligation using LigationKit ver. 2 (manufactured by Takara Shuzo Co., Ltd.). The resultingplasmid DNA was transformed with Escherichia coli (DH5α strain). Thethus obtained recombinant Escherichia coli was smeared onto an LB agarmedium containing 50 μg/mL of kanamycin and 50 μg/mL of X-Gal. Cloneswhich had formed a white colony on the medium were subjected to liquidculture in the usual way, and the plasmid DNA was then purified. Theresulting plasmid DNA was cleaved with restriction enzymes SacI andSphI, whereby about 1.75 kb of an inserted fragment was recognized andnamed pMJPC 17.2.

(C) Fabrication of PC-Enhanced Strain:

A plasmid DNA to be used for transformation of the Brevibacterium flavumMJ233/ALDH (lactate dehydrogenase gene-disrupted strain, seeJP-A-2005-95169) was reprepared from an Escherichia coli JM110 straintransformed with the plasmid DNA of pMJPC17.2 by a calcium chloridemethod (see Journal of Molecular Biology, 53, 159, 1970). Thetransformation of the Brevibacterium flavum MJ233/ALDH strain wasperformed by an electric pulse method (see Res. Microbiol., Vol. 144,pages 181 to 185, 1993), and the resulting transformant was smeared ontoan LBG agar medium [obtained by dissolving 10 g of tryptone, 5 g ofyeast extract, 5 g of NaCl, 20 g of glucose and 15 g of agar in 1 L ofdistilled water) containing 50 μg/mL of kanamycin.

Since the strain grown on this medium was an unreplicable plasmid forpMJPC 17.2 in the Brevibacterium flavum MJ233 strain bacterial cell,homologous recombination was caused between the PC gene on the subjectplasmid and the same gene on the genome of the Brevibacterium flavumMJ233 strain. As a result, kanamycin-resistant gene and sacB geneoriginated from the subject plasmid must be inserted on the genome.

Subsequently, the foregoing strain obtained by homologous recombinationwas subjected to liquid culture on an LBG medium containing 25 μg/mL ofkanamycin. The culture solution corresponding to about 1,000,000bacterial cells was smeared onto an LBG medium containing 10% sucrose.As a result, about several ten strains which were presumed to besucrose-insensitive as a result of loss of the sacB gene caused by thesecond homologous recombination were obtained. The thus obtained strainsinclude a strain in which the TZ4 promoter originated from pMJPC17.2 hasbeen inserted in the upstream of the PC gene and a strain which hasreverted to a wild type.

Whether the PC gene is a promoter substitution type or a wild type canbe easily confirmed by providing a bacterial cell obtained by liquidculture on an LBG medium directly for a PCR reaction and detecting thePC gene. When the TZ4 promoter and the PC gene are analyzed usingprimers for PCR amplification (SEQ ID NO: 8 and SEQ ID NO: 9), 678 bp ofthe DNA fragment must be recognized in the promoter substitution type.As a result of analysis of the sucrose-insensitive strain by theforegoing method, a strain having the TZ4 promoter inserted thereintowas selected, and the subject strain was named Brevibacterium flavumMJ233/PC-5/ALDH.

<Preparation of Succinic Acid Fermenting Strain by Jar Fermentor>

(A) Seed Culture:

100 mL of a medium prepared by dissolving 4 g of urea, 14 g of ammoniumsulfate, 0.5 g of monopotassium phosphate, 0.5 g of dipotassiumphosphate, 0.5 g of magnesium sulfate heptahydrate, 20 mg of ferroussulfate heptahydrate, 20 mg of manganese sulfate hydrate, 200 μg ofD-biotin, 200 μg of thiamin hydrochloride, 1 g of yeast extract, and 1 gof casamino acid in distilled water to make to 1,000 mL was charged in a500-mL Erlenmeyer flask and then sterilized by heating at 121° C. for 20minutes. This was cooled to room temperature, to which was then added 4mL of a % glucose aqueous solution having been sterilized in advance.The above-constructed Brevibacterium flavum MJ233/PC-5/ALDH wasinoculated, thereby achieving seed culture while shaking (160 rpm) at30° C. for 16 hours.

(B) Main Culture:

2.0 L of a medium prepared by dissolving 3.0 g of ammonium sulfate, 6.7g of 85% phosphoric acid, 4.9 g of potassium chloride, 1.5 g ofmagnesium sulfate heptahydrate, 120 mg of ferrous sulfate heptahydrate,120 mg of manganese sulfate hydrate, 30.0 g of a corn steep liquid(manufactured by Oji Cornstarch Co., Ltd.), 11.0 g of a 10 N potassiumhydroxide aqueous solution, and 2.5 g of an antifoaming agent (CE457,manufactured by NOF Corporation) in distilled water was charged in a 5-Lfermentor and then sterilized by heating at 121° C. for 20 minutes.

This was cooled to room temperature, to which was then added 28% ammoniawater was added to regulate the pH to 7.0. Thereafter, 15 mL of a 0.2g/L aqueous solution of each of D-biotin having been filter sterilizedin advance and thiamine hydrochloride and 110 mL of a 720 g/L sucroseaqueous solution having been sterilized in advance were added. 100 mL ofthe foregoing seed culture solution was further added thereto, and themixture was kept at 30° C. The pH was kept at not more than 7.2 using28% ammonia water, aeration was carried out at a rate of 3.0 L perminute and at a back pressure of 0.05 MPa, and stirring was carried outat 750 rpm, thereby starting main culture.

After the dissolved oxygen concentration decreased to substantially 0,an increase of the dissolved oxygen concentration again started. Whenthe dissolved oxygen concentration reached 1 ppm, about 5.3 g of a 72%sucrose aqueous solution having been sterilized in advance was added. Asa result, the dissolved oxygen concentration again decreased to 0. Theaddition of a sucrose aqueous solution was repeated by the foregoingmethod at every time when the dissolved oxygen concentration againincreased. The operation was continued until 19 hours after the start ofculture.

(C) Succinic Acid Forming Reaction:

1.6 g of 85% phosphoric acid, 1.1 g of magnesium sulfate heptahydrate,43 mg of ferrous sulfate heptahydrate, 43 mg of manganese sulfatehydrate, and 2.86 g of a 10 N potassium hydroxide aqueous solution weredissolved in distilled water to make to 42 mL, which was then sterilizedby heating at 121° C. for 20 minutes, thereby fabricating a reactionconcentrated medium.

42 mL of the foregoing reaction concentrated medium having been cooledto room temperature, 530 mL of a 720 g/L sucrose aqueous solution havingbeen sterilized in advance, 1.2 L of sterilized water, 20 mL of a 0.2g/L aqueous solution of each of D-biotin having been filter sterilizedin advance and thiamine hydrochloride, and 675 mL of the culturesolution obtained by the foregoing main culture were added in a 5-L jarfermentor, thereby starting a reaction. The reaction was continued at areaction temperature of 40° C. and at a stirring rotation number of 150rpm while regulating the pH to 7.35 by successive addition of aneutralizing agent (ammonium hydrogencarbonate: 171 g, 28% ammoniawater: 354 g, distilled water: 529 g), and when the residual sucrose inthe reaction liquid reached not more than 0.1 g/L, the reaction wascompleted.

The thus prepared reaction liquid was centrifuged (15,000 G for 5minutes) to obtain a supernatant (hereinafter sometimes referred to as“succinic acid fermentation liquid”). Results of composition analysis ofthis supernatant are shown in the following Table 2.

TABLE 2 Composition of succinic acid fermentation liquid AccumulatedAccumulated concentration concentration Product (g/L) (% by weight)Succinic acid 91.3 8.65 Malic acid 9.8 0.93 Pyruvic acid 0.5 0.05 Aceticacid 13.2 1.25 Fumaric acid 2.7 0.26 α-Ketoglutaric acid 1.1 0.10α-Ketovaline 1.1 0.10 Alanine 2.5 0.24 Valine 0.8 0.08 Glutamic acid 0.10.01 Trehalose 1.2 0.11 Protein 1.2 0.11 (Density: 1.056 g/mL)

The analysis of each of the organic acid and the sugar was carried outby means of high-performance liquid chromatography under conditionsequal to those described below.

Column: ULTRON PS-80H, 8.0 mm I.D.×30 cm, manufactured by ShinwaChemical Industries Ltd.

Temperature: 60° C.

Eluent: 0.1% perchloric acid aqueous solution, 1.0 mL/min

Injection: 3 μL

Detection: RI detector or UV detector

Detection limit of malic acid: 100 ppm

Referential Example 2

Succinic acid was produced from the thus obtained succinic acidfermentation liquid that is an aqueous solution containing an aliphaticdicarboxylic acid obtained from a raw material derived from biomassresources.

<Protonation Step>

To 1,500 g of the foregoing succinic acid fermentation liquid, 98%sulfuric acid was added, thereby regulating the pH to 2.5. Here, anaddition amount of 98% sulfuric acid was 150 g.

<Extraction Step>

The succinic acid aqueous solution after adding sulfuric acid was mixedwith a methyl ethyl ketone (hereinafter sometimes abbreviated as “MEK”)using a jacketed static mixture (Noritake ¼(1)-N40-174-0 (insidediameter ϕ: 5 mm, element number: 24)) and a jacketed three-tank typesettler in which the tanks had a volume of 600 mL, 400 mL, and 300 mL,respectively, followed by liquid-liquid separation to continuouslyextract succinic acid.

That is, 1,650 g of the succinic acid aqueous solution and 825 g of a10% hydrated MEK solution having been added with water in advance (MEKsolution (weight)/succinic acid aqueous solution (weight)=0.5(weight/weight)) were fed at a rate of 20 g/min and 10 g/min,respectively into the static mixed, the temperature of which wascontrolled while allowing warm water at 30° C. to pass through thejacket. The discharged suspension liquid was fed into the first tank ofthe three-tank type settler, the temperature of which was controlledwhile allowing warm water at 30° C. to pass through the jacket, andsubjected to liquid-liquid separation to continuously discharge araffinate phase from the bottom of the first tank.

An extract phase was overflowed from a weir between the first tank andthe second tank and fed into the second tank. In the second tank, aninsoluble component which had not been able to be separated in the firsttank was settled in the bottom, and only a clear extract phase wasoverflowed from a weir between the second tank and the third tank andfed into the third tank. Furthermore, in the third tank, a clear extractphase was overflowed from the neighborhood of a liquid-liquid interfaceto recover the extract phase. Finally, 688 g of the extract phase, 1,613g of the raffinate phase, and 173 g of an intermediate phase wererecovered. The intermediate phase was subjected to pressure filtrationwith a PTFE-made membrane filter having an opening of 0.5 μm, therebyrecovering 172 of a clear liquid.

<Continuous Extraction>

1,613 g of the recovered raffinate phase was continuously extracted with1,613 g of 10% hydrated MEK (MEK solution (weight)/succinic acid aqueoussolution (weight)=1.0 (weight/weight)) by using a jacketed stirring typecontinuous extraction column having an inside diameter ϕ of 20 mm and aheight of 2 m (theoretical plate number: 10 plates).

Here, the raffinate phase was fed at a rate of 200 g/hr from the columntop, and an MEK solution in which the water content had been regulatedto 10% by weight in advance was flown at a rate of 200 g/hr from thecolumn bottom. A continuous phase was the raffinate phase, whereas adispersed phase was the MEK phase (light liquid dispersion). Inaddition, the temperature of the extraction column was controlled to 30°C. by allowing warm water to pass through the jacket. Finally, 1,777 gof the extract phase was recovered.

The recovered extract phase was combined with the clear liquid recoveredby the mixer-settler, and the resulting aliphatic dicarboxylicacid-containing liquid was 2,637 g in total. As a result of analyzing acomposition thereof, results shown in the following Table 3 wererevealed. The analysis of each of the organic acid and the sugar wascarried out by means of high-performance liquid chromatography underconditions equal to those in Table 2.

TABLE 3 Composition of mixed solution of extract phase and clear liquidComponent Composition (% by weight) Succinic acid 4.91 Malic acid 0.19Pyruvic acid 0.00 Acetic acid 0.71 Fumaric acid 0.15 α-Ketoglutaric acid0.01 α-Ketovaline 0.02 Alanine 0.00 Valine 0.00 Glutamic acid 0.00Trehalose 0.00 Protein 0.01 MEK 80.8 Water 13.2<Distillation>

MEK is substantially removed from the recovered extract phase by meansof continuous distillation. Here, the distillate is recovered as anazeotropic composition of MEK and water, namely 11% by weight hydratedMEK; however, there is a concern that succinic acid is depositeddepending upon a degree of concentration of the still residue liquid.Then, 190 g of water was added to 2,637 g of the extract phase such thatthe distillate was 11% by weight MEK, and the still residue liquid was a30% by weight succinic acid solution.

For the distillation, an atmospheric continuous distillation apparatusequipped with a packed column having an inside diameter ϕ of 40 mm, inwhich a coil pack of ϕ5 mm was packed to a height of 30 cm, a 500-mLround-bottom flask, and a reflux condenser was used. As to thedistillation, after making the inside of the system stable by means oftotal reflux, continuous distillation was carried out at a reflux ratioof 1. The still residue liquid after the distillation was 432 g. Inaddition, results obtained by analyzing a composition thereof are shownin the following Table 4.

TABLE 4 Composition of still residue liquid after distillation ComponentComposition (% by weight) Succinic acid 30.0 Malic acid 1.14 Pyruvicacid 0.00 Acetic acid 4.31 Fumaric acid 1.14 α-Ketoglutaric acid 0.05α-Ketovaline 0.14 Alanine 0.01 Valine 0.01 Glutamic acid 0.00 Trehalose0.00 Protein 0.08 MEK 0.03<Crystallization>

The liquid from which MEK had been distilled off was transferred into ajacketed 500-mL separable flask and kept at 80° C. with stirring whileallowing warm water to pass through the jacket. Thereafter, the warmwater to be allowed to pass through the jacket was cooled to 20° C. overone hour using programmed circulating water baths, thereby crystallizingsuccinic acid under cooling, and after the temperature reached 20° C.,the system was aged at 20° C. for one hour. The resulting slurry wasfiltered in vacuo to separate a crystallization mother liquid.

Furthermore, the resulting wet cake as a crystallization product waswashed with 250 g of cold water, and the washings were recovered toobtain a wet cake composed mainly of succinic acid. Furthermore, theresulting wet cake was dried at 80° C. under a maximum pressurereduction condition using a vacuum dryer, and 114 g of succinic acid wasfinally recovered. Results obtained by analyzing a composition of theresulting succinic acid are shown in the following Table 5. The analysisof each of the organic acid and the sugar was carried out by means ofhigh-performance liquid chromatography under conditions equal to thosein Table 2.

TABLE 5 Composition of obtained succinic acid Component Composition (%by weight) Succinic acid 95.7  Malic acid 0.0 Pyruvic acid 0.0 Aceticacid 0.1 Fumaric acid 3.3 α-Ketoglutaric acid 0.0 α-Ketovaline 0.0Alanine 0.0 Valine 0.0 Glutamic acid 0.0 Trehalose 0.0 Protein 18 ppmMEK 0.0 Water 0.8 Succinic acid yield 84%

The crystallization mother liquid and the washings were mixed to prepare562 g of a recovered liquid, and a composition thereof is shown in thefollowing Table 6. The analysis of each of the organic acid and thesugar was carried out by means of high-performance liquid chromatographyunder conditions equal to those in Table 2.

TABLE 6 Composition of recovered liquid Component Composition (% byweight) Succinic acid 3.66 Malic acid 0.87 Pyruvic acid 0.00 Acetic acid3.29 Fumaric acid 0.01 α-Ketoglutaric acid 0.04 α-Ketovaline 0.10Alanine 0.01 Valine 0.01 Glutamic acid 0.00 Trehalose 0.00 Protein 0.06MEK 0.02

Referential Example 3

<Protonation>

To 1,384 g of the foregoing succinic acid fermentation liquid, 98%sulfuric acid was added, thereby regulating the pH to 2.5. Here, anaddition amount of 98% sulfuric acid was 138 g. To this protonatedliquid, 281 g of the recovered liquid recovered in Referential Example2, the amount of which is corresponding to a half thereof, was added toprepare 1,803 g of a succinic acid aqueous solution.

<Extraction>

The succinic acid aqueous solution was extracted with 10% hydrated MEKin the same method as that in Referential Example 2. In themixer-settler, 10% hydrated MEK in an amount of 0.5 weight times thesuccinic acid aqueous solution was fed at a rate of 20 g/min and 10g/min, respectively. The recovered intermediate phase was subjected topressure filtration, and the raffinate phase was further subjected tocountercurrent multi-stage continuous extraction with 10% hydrated MEKin an amount of 1.0 weight time the raffinate phase. As a result, 2,882g of the extract phase and 1,593 g of the raffinate phase wererecovered. A composition thereof is as follows.

<Distillation>

Distillation was carried out in the same method as that in ReferentialExample 2, thereby recovering 438 g of a succinic acid concentratedliquid. A composition thereof is shown in the following Table 7. Theanalysis of each of the organic acid and the sugar was carried out bymeans of high-performance liquid chromatography under conditions equalto those in Table 2.

TABLE 7 Composition of succinic acid concentrated liquid Extract phaseConcentrated liquid Component Composition (% by weight) Succinic acid4.51 29.7 Malic acid 0.19 1.24 Pyruvic acid 0.00 0.00 Acetic acid 0.926.03 Fumaric acid 0.12 0.81 α-Ketoglutaric acid 0.01 0.05 α-Ketovaline0.02 0.15 Alanine 0.00 0.01 Valine 0.00 0.01 Glutamic acid 0.00 0.00Trehalose 0.00 0.00 Protein 0.01 0.08 MEK 81.0 03 Water 13.2 —<Crystallization>

Crystallization was carried out in the same method as that inReferential Example 2, thereby recovering 113 g of succinic acid and 568g of a recovered liquid that is a mixed liquid of a crystallizationmother liquid and washings. A composition of the resulting succinic acidis shown in the following Table 8, and a composition of the resultingrecovered liquid is shown in the following Table 9. The analysis of eachof the organic acid and the sugar was carried out by means ofhigh-performance liquid chromatography under conditions equal to thosein Table 2.

TABLE 8 Composition of obtained succinic acid Component Composition (%by weight) Succinic acid 95.9  Malic acid 0.0 Pyruvic acid 0.0 Aceticacid 0.1 Fumaric acid 3.1 α-Ketoglutaric acid 0.0 α-Ketovaline 0.0Alanine 0.0 Valine 0.0 Glutamic acid 0.0 Trehalose 0.0 Protein 18 ppmMEK 0.0 Water 0.8

Recovered succinic acid/newly fed succinic acid:113×0.959/(1,384×0.0865)=91%

TABLE 9 Composition of recovered liquid Component Composition (% byweight) Succinic acid 3.63 Malic acid 0.95 Pyruvic acid 0.00 Acetic acid4.62 Fumaric acid 0.01 α-Ketoglutaric acid 0.04 α-Ketovaline 0.11Alanine 0.01 Valine 0.01 Glutamic acid 0.00 Trehalose 0.00 Protein 0.06MEK 0.02<Highly Purification>

A 30 wt % crude succinic acid aqueous solution was prepared from theabove-obtained crude crystal at 80° C., and a chemically activated,powdered activated carbon Diahope 8ED (manufactured by Calgon MitsubishiChemical Corporation) was then added in an amount of 0.3 wt % relativeto the succinic acid. The activated carbon treatment was carried out at80° C. for 2 hours with stirring at 200 rpm using a three-one motor.

After filtering out the activated carbon at 80° C., the resultingsuccinic acid aqueous solution was charged in an SUS 316-made 500-mLinduction stirring autoclave and subjected to a hydrogen treatment inthe presence of 5% Pd/C (Wako's catalogue 326-81672, catalyst amount:0.06 wt % relative to succinic acid) under a condition at a hydrogenpressure of 0.8 MPa at a reaction temperature of 80° C. for a reactiontime of 3 hours. As a result, fumaric acid contained in an amount of1.3% by weight relative to succinic acid in crude succinic acid wasentirely derived into succinic acid. After completion of the reaction,the catalyst was filtered out. The hydrogen treatment solution wassubstantially free from an odor.

This hydrogen-treated succinic acid aqueous solution was subjected to anion exchange treatment (cation exchange resin (Diaion SK1B-H(manufactured by Mitsubishi Chemical Corporation): H type) at 80° C.,thereby removing cations having been contained in a trace amount.

The ion exchange-treated succinic acid aqueous solution was cooled to20° C. with stirring for about 90 minutes and further kept at 20° C. forone hour to deposit a crystal. The deposited succinic acid was recoveredby means of filtration, and the crystal was washed with cold water andthen dried in vacuo at 70° C. for 12 hours to obtain white odorlesssuccinic acid (YI=−1).

In the resulting succinic acid, the concentrations of Na, K, Mg, Ca andNH₄ ions were all not more than 1 ppm; the sulfur atom content was lessthan 1 ppm; and the nitrogen atom content was 2 ppm. In addition, asuccinic acid aqueous solution having a concentration of the resultingsuccinic acid of 3.0 wt % was prepared, a spectrum of which was thenmeasured using a Hitachi's spectrophotometer Hitachi UV-3500. As aresult, its average absorbance at 250 to 300 nm was not more than 0.01.

Example 1

<Production of Polyester Polyol>

In a one-liter four-necked flask installed with a thermometer, aninduction stirrer, a condenser-equipped oil-water separator, and adropping funnel, 260 g (2.2 moles) of succinic acid having a content ofmalic acid of 0.2 ppm (prepared by purifying succinic acid as producedby the fermentation method) and 296 g (2.5 moles) of3-methyl-1,5-pentanediol as a polyhydric alcohol were charged.Thereafter, operations of pressure reduction to 30 Torr and pressurereturn with nitrogen were repeated several times, thereby substitutingthe inside of the reactor with nitrogen.

The temperature was increased to 145° C. while stirring the reactionmixture, and stirring was kept at that temperature for 30 minutes. Atthat time, since formed water started to come out, the removal of waterformed from the condenser-equipped oil-water separator was started.Thereafter, the temperature was increased to 220° C. over about onehour. Thereafter, 15 mL of toluene was added from the dropping funnel,the pressure was further reduced to about 600 Torr, and the removal offormed water was continued so as to reflux toluene through thecondenser-equipped oil-water separator.

15 minutes after starting the pressure reduction, 0.53 mL of atetraisopropoxy titanium (TPT) 5 wt/vol % toluene solution was added.Thereafter, when it was confirmed that the acid number became not morethan 0.50 KOH-mg/g, the reaction was completed.

After completion of the reaction, the temperature was decreased to 160°C., the pressure was further reduced finally to 20 Torr to completelydistil off the toluene, and a hydroxyl number of the contents in theflask was measured. For the purpose of obtaining a polyester polyolhaving a number average molecular weight of 2,000, in the case where thehydroxyl number is larger than 56.0, the removal of the diol was furthercarried out; whereas in the case where the hydroxyl number is smallerthan 56.0, the raw material polyhydric alcohol was added so as tocorrespond to the hydroxyl number of 56.0, and superheating was carriedout with stirring at 220° C. for an arbitrary period of time to achievea depolymerization reaction, thereby regulating the hydroxyl number toabout 56.0. As a result, a polyester polyol having a hydroxyl number of54.9 (hydroxyl number-calculated molecular weight: 2,044) was produced.The resulting polyester polyol had an APHA of 20.

The hydroxyl number-calculated molecular weight as referred to hereinwas calculated in the following manner while considering the polyol as adiol.Hydroxyl number-calculated molecular weight=[Molecular weight of KOH(g/mole)]/[Hydroxyl number (mg-KOH/g)]×1,000×2<NMR Measuring Method of Polyester Polyol>

43.3 mg of a polyester polyol sample was dissolved in 0.7 mL ofdeuteriochloroform (containing 0.05 v/v TMS) and then transferred intoan NMR sample tube having an outside diameter of 5 mm A 1H-NMR spectrumwas measured at room temperature using an AVANCE 400 spectrometer,manufactured by Bruker. As a standard of the chemical shift, a signal ofTMS was defined as 0.00 ppm. In the measurement of an amount of malicacid in the succinic acid unit of the polyester polyol, a peak of themaleate is detected at 5.43 ppm. In the case of S/N=3, a detection limitwas 500 ppm relative to the succinic acid unit.

In consequence, since the charge amount of the malic acid unit relativeto the raw material succinic acid unit was 0.2 ppm, and in the foregoingNMR measurement, the detection limit of malic acid was 500 ppm, andhence, the malic acid unit was not detected.

<Polyurethane Production 1>

In a one-liter separable flask, 102.2 g of the polyester polyol producedby the foregoing method (number average molecular weight calculated fromthe hydroxyl number: about 2,000) was charged and dissolved inN,N-dimethylformamide (DMF) by dipping the flask on an oil bath set at55° C. while heating. Stirring was started at about 100 rpm, 4.51 g of1,4-butanediol was further added as a chain extender, and 0.024 g of tinoctylate was dropped.

Subsequently, diphenylmethane diisocyanate (MDI) was dropped at a ratesuch that the reaction liquid temperature did not exceed 70° C.Thereafter, MDI was gradually dropped to achieve chain extension, andfinally, 25.3 g (1.01 equivalents to the polyol hydroxyl group) of MDIwas added. When it was confirmed that the weight average molecularweight exceeded 100,000 by the GPC measurement, the reaction wascompleted to obtain a DMF solution of polyurethane having a solidcontent of 30%. The resulting polyurethane revealed target results suchthat a weight average molecular weight was 139,000, and a molecularweight distribution Mw/Mn was 2.1.

<NMR Measuring Method of Polyurethane>

About 40 mg of a polyurethane sample was weighed in an NMR sample tubehaving an outside diameter of 5 mm and dissolved in about 1.0 mL ofDMF-d7. A 1H-NMR spectrum was measured at room temperature using anAVANCE 400 spectrometer, manufactured by Bruker. As a standard of thechemical shift, a signal on the low magnetic field side of a methylgroup of DMF was defined as 2.91 ppm. In the measurement of an amount ofmalic acid in the succinic acid unit of the polyurethane, a peak of themaleate is detected at 5.46 ppm. In the case of S/N=3, a detection limitwas 300 ppm relative to the succinic acid unit. In consequence, sincethe charge amount of the malic acid unit relative to the raw materialsuccinic acid unit was 0.2 ppm, and in the foregoing NMR measurement,the detection limit of malic acid was 300 ppm, and hence, the malic acidunit was not detected.

<Fabrication of Sample for Evaluating Polyurethane Physical Properties>

The resulting polyurethane solution was used and coated in a uniformfilm thickness on a polyethylene film using a doctor blade, followed bydrying by a dryer to obtain a polyurethane film. A tensile strength testof this film was carried out according to the foregoing measuringmethods of film physical properties. As to the physical properties, theurethane film had a stress at break of 7.9 MPa and had a low elasticmodulus such that an elongation at break was 1,270%, thereby revealingvery excellent physical properties in elongation.

Comparative Example 1

A polyester polyol having a hydroxyl number of 55.1 (hydroxylnumber-calculated molecular weight: 2,036) was produced by theabove-described polyester polyol production method by using, as rawmaterials, 260 g (2.2 moles) of succinic acid having a content of malicacid of 5,000 ppm (using commercially available succinic acid asproduced from maleic anhydride as a raw material) and 296 g (2.5 moles)of 3-methyl-1,5-pentanediol as a polyhydric alcohol. This polyesterpolyol had an APHA of 20. As a result of the NMR measurement, an amountof a malic acid unit, namely a crosslinking structure, was 0.47% by molerelative to a succinic acid unit.

A polyurethane was produced in the above-described production method ofPolyurethane Production 1 by using 101.8 g of the foregoing polyesterpolyol as a raw material, 4.51 g of 1,4-butanediol as a chain extender,and 25.2 g (1.01 equivalents to the hydroxyl group) of diphenylmethanediisocyanate (MDI).

The resulting polyurethane had a weight average molecular weight of410,000 and a molecular weight distribution Mw/Mn of 3.2 and revealedresults that both the molecular weight and the molecular weightdistribution were unexpectedly large. As a result of the NMRmeasurement, an amount of a malic acid unit, namely a crosslinkingstructure, was 0.52% by mole relative to a succinic acid unit. Inaddition, the urethane film had a stress at break of 9.9 MPa and had ahigh elastic modulus such that an elongation at break was 910%, therebyrevealing low physical properties in elongation.

Comparative Example 2

A polyester polyol having a hydroxyl number of 54.1 (hydroxylnumber-calculated molecular weight: 2,074) was produced by theabove-described polyester polyol production method by using, as rawmaterials, 260 g (2.2 moles) of succinic acid having a content of malicacid of 1,700 ppm (succinic acid prepared by purifying a productproduced from maleic anhydride as a raw material was used) and 296 g(2.5 moles) of 3-methyl-1,5-pentanediol as a polyhydric alcohol. Thispolyester polyol had an APHA of 20. As a result of the NMR measurement,an amount of a malic acid unit, namely a crosslinking structure, was0.16% by mole relative to a succinic acid unit.

A polyurethane was produced in the above-described production method ofPolyurethane Production 1 by using 103.7 g of the foregoing polyesterpolyol as a raw material, 4.51 g of 1,4-butanediol as a chain extender,and 25.3 g (1.01 equivalents to the hydroxyl group) of diphenylmethanediisocyanate (MDI).

The resulting polyurethane had a weight average molecular weight of320,000 and a molecular weight distribution Mw/Mn of 2.8 and revealedresults that both the molecular weight and the molecular weightdistribution were unexpectedly large. As a result of the NMRmeasurement, an amount of a malic acid unit, namely a crosslinkingstructure, was 0.19% by mole relative to a succinic acid unit. Inaddition, in this urethane solution, the weight average molecular weightabnormally increased to 490,000 at the time of film fabrication, andhence, the evaluation was discontinued.

Example 2

A polyester polyol having a hydroxyl number of 61.0 (hydroxylnumber-calculated molecular weight: 1,839) was produced in the samemethod as that in Example 1, except for using, as raw materials, 71 g(0.6 moles) of succinic acid having a content of malic acid of 0.2 ppm(prepared by purifying succinic acid as produced by the fermentationmethod), 88 g (0.6 moles) of adipic acid (commercially availableproduct), and 162 g (1.4 moles) of 3-methyl-1,5-pentanediol as apolyhydric alcohol. This polyester polyol had an APHA of 25, and evenwhen mixed with a petroleum-derived dicarboxylic acid, a polyesterpolyol with less coloration was obtained.

Example 3

A polyester polyol having a hydroxyl number of 56.9 (hydroxylnumber-calculated molecular weight: 1,972) was produced in the samemethod as that in Example 1, except for using, as raw materials, 160 g(1.4 moles) of succinic acid having a content of malic acid of 500 ppm(prepared by adding malic acid to succinic acid as produced by thefermentation method) and 179 g (1.5 moles) of 3-methyl-1,5-pentanediolas a polyhydric alcohol; and setting an upper limit of the reactiontemperature to about 190° C.

<Polyurethane Production 2>

In a one-liter separable flask, 56.8 g of the polyester polyol producedby the foregoing method (number average molecular weight calculated fromthe hydroxyl number: about 2,000) was charged and substituted withnitrogen three times. Thereafter, the pressure was reduced to 20 Torr,and the flask was dipped on an oil bath at 100° C. to achievedehydration for one hour. After lapsing one hour, the system was oncecooled, and the pressure was returned with nitrogen. At that time, awater content of the polyester polyol was 110 ppm. Subsequently, theflask was dipped on an oil bath at 60° C., and N,N-dimethylacetamide(DMAc) was added and dissolved while heating. Stirring was started atabout 100 rpm, 2.55 g of 1,4-butanediol was further added as a chainextender, and 0.012 g of tin octylate was dropped. At that time, thewater content was 0.025 g (0.0014 moles) in total in the polyesterpolyol and the solvent.

In the polyurethane reaction, since MDI is consumed by water containedin the system, the addition amount of MDI was determined taking intoconsideration the water content. The water content after dehydrating thepolyol and the water content contained in the used solvent weremeasured, and MDI was added through calculation such that its additionamount was 100% relative to the hydroxyl group number of the polyesterpolyol and the chain extender and the active hydrogen number containedin the measured water content (MDI equivalent to the active hydrogen).

That is, the MDI equivalent to the active hydrogen is expressed by thefollowing equation.MDI equivalent relative to active hydrogen=(NCO [mole])/{(Hydroxyl groupnumber of polyester polyol [mole])+(Hydroxyl group number of chainextender [mole])+(Water content in polyester polyol [mole])+(Watercontent in solvent [mole])}

Diphenylmethane diisocyanate (MDI) was dropped at a rate such that thereaction liquid temperature did not exceed 70° C. Thereafter, MDI wasgradually dropped to achieve chain extension, and finally, 14.4 g (1.00equivalent to the active hydrogen) of MDI was added. When it wasconfirmed that the weight average molecular weight exceeded 100,000 bythe GPC measurement, the reaction was completed, thereby obtaining aDMAc solution of polyurethane having a solid content of 30%.

The resulting polyurethane revealed results such that a weight averagemolecular weight was 188,000, and a molecular weight distribution Mw/Mnwas 2.0. In addition, as to the physical properties, the urethane filmhad a stress at break of 8.5 MPa. In addition, in the case of producinga polyurethane in the same method as Polyurethane Production 2, exceptthat in the foregoing polyurethane reaction, 14.5 g (1.01 equivalents tothe active hydrogen) of diphenylmethane diisocyanate (MDI) was used, andthe resulting polyurethane revealed results such that a weight averagemolecular weight was 258,000, and a molecular weight distribution Mw/Mnwas 2.2. Thus, a polyurethane having a desired molecular weight waseasily obtainable without causing gelation.

Example 4

A polyester polyol having a hydroxyl number of 52.6 (hydroxylnumber-calculated molecular weight: 2,133) was produced in the samemethod as that in Example 1, except for using, as raw materials, 160 g(1.4 moles) of succinic acid having a content of malic acid of 0.2 ppm(prepared by purifying succinic acid as produced by the fermentationmethod) and 178 g (1.5 moles) of 3-methyl-1,5-pentanediol as apolyhydric alcohol.

A polyurethane was produced in the above-described production method ofPolyurethane Production 2 by using 60.2 g of the foregoing polyesterpolyol as a raw material, 2.54 g of 1,4-butanediol as a chain extender,and 14.2 g (1.00 equivalent to the active hydrogen) of diphenylmethanediisocyanate (MDI). At that time, the water content was 0.014 g (0.00078moles) in total in the polyester polyol and the solvent. The resultingpolyurethane revealed target results such that a weight averagemolecular weight was 160,000, and a molecular weight distribution Mw/Mnwas 2.0. In addition, as to the physical properties, the urethane filmhad a stress at break of 5.5 MPa.

In addition, in the case of producing a polyurethane in the same methodas Polyurethane Production 2, except that in the foregoing polyurethanereaction, 14.3 g (1.01 equivalents to the active hydrogen) ofdiphenylmethane diisocyanate (MDI) was used, and the resultingpolyurethane revealed results such that a weight average molecularweight was 201,000, and a molecular weight distribution Mw/Mn was 2.0.Thus, a polyurethane having a desired molecular weight was easilyobtainable without causing gelation.

Comparative Example 3

A polyester polyol having a hydroxyl number of 55.2 (hydroxylgroup-calculated molecular weight: 2,033) was produced in the samemethod as that in Example 1, except for using, as raw materials, 160 g(1.4 moles) of succinic acid having a content of malic acid of less thanthe detection limit (succinic acid prepared by further crystallizationand purification of succinic acid having a malic acid content of 0.2 ppmas produced by the fermentation method, thereby making the malic acidcontent less than the detection limit relative to succinic acid byLC-MS, was used) and 177 g (1.5 moles) of 3-methyl-1,5-pentanediol as apolyhydric alcohol; and setting an upper limit of the reactiontemperature to about 190° C.

A polyurethane was produced in the above-described production method ofPolyurethane Production 2 by using 58.9 g of the foregoing polyesterpolyol as a raw material, 2.61 g of 1,4-butanediol as a chain extender,and 14.7 g (1.00 equivalent to the active hydrogen) of diphenylmethanediisocyanate (MDI). At that time, the water content in the system was0.028 g (0.0016 moles) in total in the polyester polyol and the solvent.

The resulting polyurethane had a weight average molecular weight was146,000, and a molecular weight distribution Mw/Mn of 2.1 and revealedresults that the molecular weight hardly increased. In addition, theurethane film had a stress at break of 5.3 MPa, so that a polyurethanewith sufficient mechanical strength was not obtained.

Comparative Example 4

A polyester polyol having a hydroxyl number of 56.3 (hydroxylnumber-calculated molecular weight: 1,993) was produced in the samemethod as that in Example 1, except for using, as raw materials, 159 g(1.4 moles) of succinic acid having a content of malic acid of 5,000 ppm(succinic acid prepared by adding malic acid to succinic acid asproduced by the fermentation method was used) and 178 g (1.5 moles) of3-methyl-1,5-pentanediol as a polyhydric alcohol; and setting an upperlimit of the reaction temperature to about 190° C.

A polyurethane was produced in the above-described production method ofPolyurethane Production 2 by using 60.7 g of the foregoing polyesterpolyol as a raw material, 2.75 g of 1,4-butanediol as a chain extender,and 15.4 g (1.00 equivalent to the active hydrogen) of diphenylmethanediisocyanate (MDI). At that time, the water content in the system was0.025 g (0.0014 moles) in total in the polyester polyol and the solvent.The resulting polyurethane had a weight average molecular weight of375,000 and a molecular weight distribution Mw/Mn of 3.2 and revealedresults that both the molecular weight and the molecular weightdistribution were unexpectedly large. As a result of the NMRmeasurement, a stress at break of the urethane film was 14.4 MPa.

In addition, in the case of producing a polyurethane in the same method,except that in the foregoing polyurethane reaction, 15.6 g (1.01equivalents to the active hydrogen) of diphenylmethane diisocyanate(MDI) was used, the polyurethane caused gelation.

That is, in the case of producing a polyester polyol using succinic acidcontaining 5,000 ppm of malic acid and subsequently producing apolyurethane, the molecular weight largely increases relative to theaddition and operation amount of MDI, resulting in danger of causinggelation. Thus, results that it is difficult to obtain a polyurethanehaving a desired molecular weight were revealed.

The results of Examples 3 to 4 and Comparative Examples 3 to 4 are shownin Table 10.

TABLE 10 Amount of malic Stress at break of acid in raw materialMolecular weight of polyurethane [Mw] polyurethane [MPa] succinic acidMDI: 1.00 MDI: 1.01 MDI: 1.00 [ppm] equivalent equivalents equivalentComparative Less than 146,000 — 5.3 Example 3 detection limit Example 40.2 160,000 201,000 5.5 Example 3 500 188,000 258,000 8.5 Comparative5,000 375,000 (Gelated) 14.4 Example 4

Example 5

<Production 2 of Polyester Polyol>

In a one-liter four-necked flask installed with a thermometer, aninduction stirrer, a condenser-equipped oil-water separator, and adropping funnel, 170 g (1.5 moles) of succinic acid having a content ofmalic acid of 0.2 ppm (prepared by purifying succinic acid as producedby the fermentation method), 110 g (1.8 moles) of ethylene glycol as apolyhydric alcohol, and 80 g (0.9 moles) of 1,4-butanediol were charged.Thereafter, operations of pressure reduction to 30 Torr and pressurereturn with nitrogen were repeated several times, thereby substitutingthe inside of the reactor with nitrogen.

The temperature was increased to 145° C. while stirring the reactionmixture, and stirring was kept at that temperature for 30 minutes. Atthat time, since formed water started to come out, the removal of waterformed from the condenser was started. Thereafter, the temperature wasincreased to 190° C. over about one hour. After the temperatureincrease, 0.35 mL of a tetraisopropoxy titanium (TPT) 5 wt/vol % toluenesolution was added. The pressure of the reactor was reduced fromordinary pressure to 20 Torr over about 2 hours, thereby removing aprescribed amount of the excessive diol together with water. Thereafter,when it was confirmed that the acid number became not more than 1.0KOH-mg/g, the reaction was completed.

After completion of the reaction, the temperature was decreased to 160°C., and a hydroxyl number of the contents in the flask was measured. Forthe purpose of obtaining a polyester polyol having a number averagemolecular weight of 2,000, in the case where the hydroxyl number islarge than 56.0, the removal of the diol was further carried out;whereas in the case where the hydroxyl number is smaller than 56.0, theraw material polyhydric alcohol was added so as to correspond to thehydroxyl number of 56.0, and superheating was carried out with stirringat 190° C. for an arbitrary period of time to achieve a depolymerizationreaction, thereby regulating the hydroxyl number to about 56.0. As aresult, a polyester polyol having a hydroxyl number of 55.8 (hydroxylnumber-calculated molecular weight: 2,011) was produced.

A polyurethane was produced in the above-described production method ofPolyurethane Production 2, except for using 58.8 g of the foregoingpolyester polyol as a raw material, 2.63 g of 1,4-butanediol as a chainextender, and 14.8 g (1.00 equivalent to the active hydrogen) ofdiphenylmethane diisocyanate (MDI) and using DMF as a solvent. At thattime, the water content was 0.029 g (0.0016 moles) in total in thepolyester polyol and the solvent. The resulting polyurethane revealedtarget results such that a weight average molecular weight was 198,000,and a molecular weight distribution Mw/Mn was 2.0. Also, an abnormalincrease of the molecular weight was not observed, and excellentproduction stability was revealed.

From the foregoing results, as shown in the present ComparativeExamples, it has been noted that in the case of producing a polyesterpolyol using, as a raw material, a dicarboxylic acid having a content ofan organic acid having a pKa value of not more than 3.7 of more than1,000 ppm and producing a polyurethane using this polyester polyol,since the produced polyester polyol and polyurethane have a crosslinkingstructure, gelation and abnormal molecular weight increase occur at thetime of polyisocyanate reaction due to the crosslinking structure, andhence, control of the reaction is difficult. Furthermore, it has beennoted that physical properties of the resulting polyurethane are rigidand low in elongation.

In addition, as shown in the present Comparative Examples, it has beennoted that in the case of producing a polyester polyol using adicarboxylic acid having a content of an organic acid having a pKa valueof not more than 3.7 of 0 ppm (less than a detection limit) andproducing a polyurethane using this polyester polyol, molecular weightsof the produced polyester polyol and polyurethane do not sufficientlyincrease, and the mechanical strength of the resulting polyurethane islowered.

On the other hand, as shown in the present Examples, it has been notedthat in the case of producing a polyester polyol using, as a rawmaterial, a dicarboxylic acid having a content of an organic acid havinga pKa value of not more than 3.7 of more than 0 ppm and not more than1,000 ppm and producing a polyurethane using this polyester polyol,since a crosslinking structure appropriately relies upon the producedpolyester polyol and polyurethane, not only the molecular weight or thelike is easily controllable at the time of polyisocyanate reaction, buta polyurethane with sufficient mechanical strength is obtained.

It has hitherto been considered that in a polyester polyol using, as araw material, succinic acid as the dicarboxylic acid, the reactioncontrol is difficult at the time of polyurethane reaction, and physicalproperties of a polyurethane using it are rigid and low in elongation.However, by using certain specified succinic acid as a raw material, ithas now been astonishingly noted that even when succinic acid is used asthe raw material, the reaction control is possible, and furthermore, apolyurethane having sufficient mechanical strength can be produced.

While the present invention has been described in detail and withreference to specific embodiments thereof, it will be apparent to oneskilled in the art that various changes and modifications can be madetherein without departing from the spirit and scope thereof.Incidentally, the present application is based on a Japanese patentapplication, filed Mar. 31, 2010 (Japanese Patent Application No.2010-082393), the entire contents of which are incorporated therein andmade hereof by reference.

INDUSTRIAL APPLICABILITY

Since a biomass-resource-derived polyurethane using, as a raw material,a biomass-resource-derived polyester polyol according to the presentinvention is easily controllable in the reaction and low in its solutionviscosity, it is good in operability and is easily cast and coated.Thus, it can be used for wide-range polyurethane applications.

Furthermore, since the polyurethane of the present invention is derivedfrom environmentally friendly plants while keeping mechanical strengthssuch as abrasion resistance, flexibility resistance, etc. ascharacteristics as conventional polyester polyol-derived polyurethanes,it is expected that the present invention is industrially extremelyuseful.

The invention claimed is:
 1. A method for producing abiomass-resource-derived polyurethane, the method comprising: reactingan organic acid having a pKa value at 25° C. of not more than 3.7, adicarboxylic acid other than the organic acid, and an aliphatic diol toproduce a polyester polyol having a number average molecular weight of500 to 4,500; and reacting the polyester polyol and a polyisocyanatecompound, to obtain the biomass-resource-derived polyurethane, whereinthe dicarboxylic acid comprises at least one component derived frombiomass resources, wherein a content of the organic acid is more than 0ppm and not more than 1,000 ppm relative to the dicarboxylic acid. 2.The method for producing a biomass-resource-derived polyurethaneaccording to claim 1, wherein the dicarboxylic acid contains succinicacid derived from biomass resources.
 3. The method for producing abiomass-resource-derived polyurethane according to claim 1, wherein theorganic acid having a pKa value at 25° C. of not more than 3.7 has threeor more active hydrogen groups per molecule.
 4. The method for producinga biomass-resource-derived polyurethane according to claim 1, whereinthe organic acid having a pKa value of the organic acid at 25° C. of notmore than 3.7 is at least one member selected from malic acid, tartaricacid, and citric acid.